Solex,
can you expand on why main chain is so important?
Does off chain imply certain limitations?
Yes, indeed.
Main-chain is so important because this is the proven technology. Satoshi's PoW model has functioned extremely well for 6.5 years. This is why when we talk about scaling main-chain volume handling we are talking about extending the capabilites of what is
known. And the quote from the Developers all refers to work which they have done to improve on Satoshi's original implemetation.
All other ideas are
unknowns: Side-chains, Tree-chains, Lightning Network. None of them are going to have a 6.5 year proven real-world live-usage track record in the face of the world's most determined hackers and spammers until 2022 at the earliest.
LN is a great idea, I like it a lot, but basic questions exist like "How safe is its version of BTC addresses?" LN allows for several hops between sender and receiver. So if you are sending BTC to "Joe Bloggs" then how secure it, when some MITM attack may route your payment to "Joe Bloggz" in Russia instead?
LN will have a federated model with far fewer nodes. Does this mean it is more vulnerable to white-listing, black-listing or tracking?
Any other 3rd party solution will always have risks, just like leaving fiat in a bank or BTC on MtGox.
Side-chains have huge promise where fundamentals can be varied, 2-minute blocks?, no problem. But how guaranteed can it be that BTC on a side-chain might not get locked permanently when a side-chain has a catastrophic failure? SC are not even considered a true scaling option.
Tree-chains have been in draft for 2 or 3 years now. They need to be in the wild for 2 or 3 years to be a viable scaling option.
There is a long road until any of them can do better than using the existing blockchain.
Remember the recent meme in the mainstream about "Blockchain tech without Bitcoin"? Well how about a new dev meme "Bitcoin without the blockchain".
Is that any better?
The comment below captures the essence of my concern:
Shmullus_ZimmermanHad to sign up for Reddit as a total newb (after lurking for years) just to post this:
Isn't the biggest concern in the 'Open Letter' (a) the fact the letter does NOT contain term "blockchain" when (b) combined with the the following language: " We’re committed to ensuring the largest possible number of users benefit from Bitcoin, without eroding these fundamental values."
What does that mean? The phrase "benefit from Bitcoin" does not convey a commitment for the maximum number of users to have access to the BLOCKCHAIN! They talk about "Bitcoin" as an amorphous concept. They talk about the "Bitcoin network" without mentioning the single-most crucial bedrock component, the block chain. The letter contains zero commitment to "scaling" involving the block chain itself.
I've dealt with lawyer-speak my entire adult career. I've seen what it looks like when folks with an agenda are trying carefully to dance around an 'elephant in the corner of the room.'
My Seat of the Pants Prediction: The workshops will turn out to focus to a troubling extent on off-chain solutions (which is to say: private for-profit enterprises building ecommerce banks off the blockchain). Implicit in off-chain solutions, so far as I can tell, will be a strong bias toward keeping the block size fixed so that you have to go to the off chain solution if you want something to occur fast. If things keep going this way, eventually talk will turn to limiting the blockchain to only transactions of "X or more" Bitcoin, with all smaller transactions kicked into the proprietary sidechains and clearing houses.
"Fast!" "Convenient!" "Backed by (but not on) the Block Chain!" I can just see it now.
