From that link:
...Only the very best investments will get funded with deflation.
I believe my post #58 in this thread addresses this. It shows that it's not only the very best investments, but also any approximately average or better ones will get funded during deflation. Furthermore, the money that would have otherwise gotten loaned instead gets hoarded, but it still provides a benefit to the economy, albeit less directly, and in ways that you can't see; it prevents the bidding up of the prices of goods in the economy that the borrower would have otherwise purchased.
First of all, I'll consider the case if/when a steady user base has formed and the adoption rate has levelled off, as this is the only case where your perpetually fixed 10% annual bitcoin supply increase might make sense. Otherwise, you're probably going to need human feedback in your system.
Yes, let's consider that case, our reasoning will be simpler.
Because the bitcoin supply will at this time be roughly fixed/very slowly increasing, any deflation will be caused by overall growth in the bitcoin economy. Thus, the deflation rate and overall growth rate are equal, modulo lost coins and short-term fluctuations in velocity.
Credit acts often as a medium of exchange, so there's inflation caused by credit growth, which will eventually become unsustainable due to the exponential nature of compound interest.
When the credit growth is not sustainable, the credit begins to shrink, causing an effective decrease on supply that leads to deflation.
So deflation is not only caused by growth and hoarding (your short-term fluctuations in velocity ?), but let's assume that's true for a while.
So if the deflation rate is steady and predictable enough (true by the above assumption), then people will only borrow to invest if they are sure their investment can at least keep up with the overall growth rate of the bitcoin economy, plus the usual premium paid for risk/time value of money/lender profit.
Why is economic growth predictable? In today's world, for example, the energy production grows exponentially, but nothing warranties that will be the case in the near future. Even if we avoid the coming energy crises through thorium based nuclear energy, why must the growth be similar to the one fueled by coil/gas/oil extraction? It could be faster or slower.
Even if growth were predictable. The risk premium must be separated from the lender's profit/"time value" of money/basic interest/liquidity premium.
While the growth and the risk premium can be equal to zero, the basic interest (with scarce and everlasting money/money-capital) cannot.
The growth can even be negative.
And if the loan is thus not made, and the money hoarded instead, then the deferred consumption that the hoarded money represents results in concomitant price decreases in the bitcoin economy that would not have occurred if the loan had been made. So the overall bitcoin economy is the beneficiary of the deferred consumption, rather than the borrower whose investment couldn't keep up with its growth rate. And this should be the case, should it not?
Here the borrower is asked to outperform the average growth (that we're assuming is equal to deflation) by basic interest (exclude the risk premium here).
The interest rate is not equal to the average growth but to the average capital yields. But capital yields are not like other profits. While profit drops to zero naturally by competition, capital yields tend to be equal to the interest rates of money, that won't ever drop to zero with everlasting money.
Thus interest on money prevents competition between real capitals. If a build a house near to yours, the capital yield of both houses (rent) will drop, and either the capital yield or the value of the house with it.
If interest rates were zero, the cost of construction of a house would tend to be equal to the amount exacted from the rent during the life of the house. But with interest rates, the demand for houses cannot be fully satisfied, because houses must be at least as profitable as money is. We're assuming free market and fixed monetary base so please don't bring the housing bubble to our reasoning.
With deflation, an investment must be at least as profitable as the interest rate plus the deflation rate (that you claim would be equal to growth).
When viewed this way, the deflation rate is seen as a valuable measure of something like the average ROI in the bitcoin economy, and loans that are made uneconomical due to it are revealed clearly by it to be just that. And there are clearly still beneficiaries of deferred consumption in the event that bitcoins are hoarded instead of lent - they are instead the bitcoin users who would have otherwise been competing to buy the goods that the borrower would have bought. They're Bastiat's "unseen", whereas the borrower would have been the "seen".
Again, the interest rates must be added to deflation.
In your example, the baker wouldn't take out the loan because his investment isn't at least as profitable as the average in the economy. He would not be buying the flour that he otherwise would have, and so more efficient bakeries can now benefit from lower flour prices due to not having to compete with the would-be baker to buy it. You might say that farmers would eventually just compensate for this increased demand, and increase supplies, but remember that this diversion of their resources would be occurring to accommodate an investment that is producing a below average return, and should perhaps not be seen as beneficial to the economy.
In my example I'm assuming that this baker is as efficient as any other baker. He can profit 5% annually (in proportion to the price of the bakery), but what's happening is that his bakery is being devalued by deflation.
The bakers that already own their bakery and don't have debts can sustain their business despite the deflation, but they may find more interesting to sell it, buy it again (at a lower price) when the deflation passes and live on the difference between both values in the meantime.
It's money against other capitals, and during deflation money is king, because it yields the same percentage and is not devalued.