I've used GDPR a few times to protect myself from nefarious actors. Its a valuable tool if you use it right, like all the things.
We had hope that it would do good and change the direction we were on. And it has been a success, the changes are industry wide and massive. Of course it isn't without faults, but we are far better off with it and have a better foundation for the future.
It isn't a cure-all but it is a whole lot better than what we had before and what exists in most other parts of the world.
EU residents are, of course, free to not do business with those they don’t want to. Likewise, businesses are free to comply or not, just as companies can choose to comply when China says to stop reporting on their human rights violations.
It applies, though indeed it doesn't matter in the immediate future because the EU won't be able to collect on it. However, I would expect it to prevent that company from ever being able to open a EU-based subsidiary in the future, so it's still a good deterrent (that is, if the GDPR was actually enforced).
In practice though, the worst offenders which the GDPR is supposed to protect us against (though again the enforcement of it leaves much to be desired) have big EU presences so it's not a problem.
> EU residents are, of course, free to not do business with those they don’t want to
The problem is that companies that the GDPR applies to seem very determined to be doing "business" with EU residents even without their knowledge or agreement. This "business" is of course about collecting, reselling or using their personal information in nefarious ways.
Indeed, if the solution was as simple as "don't do business with these companies" we would've never had the GDPR because there wasn't a need for it.