Yup, this "poisoning the well" effect is real, and it's blatantly uncompetitive - which is why it's so important for regulatory agencies to step in and act fast and hard so that this "first mover advantage" is eliminated.
The problem is, regulatory agencies are slow as molasses and courts are overloaded with crap, which means by the time the process is done years later, the companies have long since switched to yet another sleazebag tactic.
I don't want government agencies involved in dictating the minutia of acceptable UI design for a private website.
Businesses have brand reputations. Just let people vote with their wallets. That won't discourage all dark patterns, but is preferable to a world of over-regulation.
There's no point letting "people vote with their wallets" when companies have monopolies or near-monopolies due to network effects - and these shitty tactics work, so their most effective competitors are practically forced to use them to compete.
See also: Google, Amazon, etc. The laissez-faire voting with wallets approach has failed time and again. It doesn't seem to discourage dark patterns at all. I'd love to use companies with less infuriating interfaces but they can't compete.
I'm not too concerned about over-regulation. I don't think there's much innovation possible in the renting rooms to the public space; the biggest change I've seen recently is in more dark manipulation of customer behaviour. However, perhaps there's an alternative to having governments regulate UI design, like requiring 3rd-party API access.
Businesses, particularly in oligopoly/platform scenarios, don't care about brand reputation. Just look at Meta - they don't even care about billions of euros worth of GDPR fines, it's all priced in.
The problem is, regulatory agencies are slow as molasses and courts are overloaded with crap, which means by the time the process is done years later, the companies have long since switched to yet another sleazebag tactic.