The reason for this is because consumers will ultimatly act rationally and in their own best interest
Rational consumers will act rationally, but the fact that we have literally tens of thousands of complete scam tokens and coins that people continue to lose their money on, and we have 100% proven scam exchanges like YoBit still operating, proves that this space is
filled with irrational users. If any service thinks they can largely get away with doing something which will harm their user base in order to make themselves more money, then they will absolutely do that. Robinhood is a great example. Other examples which spring immediately to mind are Coinbase selling customer data without users' knowledge or consent, Binance tricking newbies in to buying some fake bitcoin token on their centralized scamchains rather than actual bitcoin, and Wasabi implementing censorship in their wallet. Plenty of people don't even know these things are happening, let alone actually care about them.
that precedent alone proves they can control what clients can do
Exactly. Any coins stored on a centralized exchange are not yours and you do not control them, which becomes obvious when exchanges like Robinhood stop you from selling them or sell them against your will.
A truly rational user would get their coins off of centralized exchanges and in to their own wallets as soon as is practical.