While people invest in alts and tokens, many treats BTC as 'stable' investment. For example, many ICOs make ESCROW in 40% BTC and then other coins.
Do you think BTC unwittingly took the role of the central bank in relation to other coins (detail, consumer 'banks')?
Oh... That's not stupid at all.
There is indeed the idea of stability and strength in BTC. More than in any altcoin.
There is this idea that to get an altcoin you sell BTC
I mean 99% of the time you just can't buy an alt with fiat, you need BTC.
I don't know if it took the role of a central bank though. But it did indeed took the role of main currency rather well. In the same way that for long all trades of currencies has to go through $, now all trades of altcoins have to go through BTC ^^