Every alt coin is priced in Satoshis on the exchanges, if Bitcoin rises and everybody held their coins, the value of alts would go up WITH BTC. And not only that, but if they held them, the alt marketcaps would grow and it would add more value and liquidity to the cryptosphere as a whole.
Your premise is dependent on the fact that the majority of alt coins holders care about the Alt coin.
The problem is the Crypto Day Traders care nothing for what they are trading, only for the small % of profit , that they can gleam from their trading.
They don't care that they are crushing a coin's price and lowering it market cap.
Until a coin's community becomes strong enough to overpower the Crypto Day Traders, price of the coin will continue to fall.
Constant supply of New Coins keep the communities members resources split between coins so that the ALTs don't make the headway they would without the interference.
It is also an Intentional Divide and Conquer Strategy , by some of the BTC Elite, to keep Alts prices in satoshi, instead of something else, BTC marketcap is being floated by the value of the Alt Market, but if the ALTS gained direct FIAT trading , BTC loses them as a float for their marketcap, as more trading will be done in Fiat.
FYI:
This is just more history repeating itself for us Old Enough to remember.
http://www.financialsense.com/contributors/jerry-robinson/the-rise-of-the-petrodollar-system-dollars-for-oilThe Same Game with a New Name: "Dollars for Oil" Replaces "Dollars for Gold"
1st BTC for Alt coins (to increase BTC Value) , so the new line will be "Dollars for BTC"
You would think they would try something new after 72 years.
But it was foretold in 1988,
https://socioecohistory.wordpress.com/2014/07/26/flashback-1988-get-ready-for-a-world-currency-by-2018%E2%80%B3-the-economist-magazine/You think
NIRP is an accident, it is the way they will Force Consumers into Crypto.
http://www.valuewalk.com/2016/05/nirp-banks-paid/http://www.marketexpress.in/2016/05/the-nirp-refugees-are-coming-to-america.html