The trouble crypto has is that it is fast to liquidate and operates 24/7. Speculators will cash out their bags to cover margin calls on their stocks. The good thing about crypto is also the bad thing about crypto. You can't do the opposite. If you're being liquidated in crypto, it would take a day to sell off stock and a few days for the transaction to settle, then maybe another day to transfer the money.
So, it's true that crypto is better than fiat. But, that's its weakness, being better than fiat. Therefore, when panic sets in, crypto is the first to be sold.