Good answer, but too detailed
TL;DR: When you buy or sell a stock, you have two days to settle. ie. I buy GME today, but I don't have to pay for it until two days from now. The broker is on the hook to make sure you pay. In a normal stock, the broker has a bunch of cancelling buy/sells so their net exposure is minimal and the volatility in the stock is reasonable. GME and others broke that mold since brokers like RH mostly had buy orders and volatility was through the roof. So RH absolutely needed more liquidity to manage their credit risk. More importantly, they should have done things like demand 100% margin for buying/selling rather than restrict buying.
RH CEO, Vlad, on CNBC yesterday was a disaster. I got the distinct impression he doesn't know how market mechanics works. Not a good look for a CEO. Trust, gone.