I wouldn't be surprised if there's some limit to prevent abuse, but it hardly gets in the way of my normal usage.
They need to support their efforts somehow. Instead of showing ads or selling your data, they are going to charge a fee to use it.
I'm logged into Google all the time. I do this to get sharing working across Chrome. Others doe the same with Firefox. Some don't, because privacy.
I hear you think logins are 1000x more hostile than paying with your eyeballs. How would you suggest resolving this clearly conflicted view with logging in vs. how the revenue is made on a given site?
But that is changing. Internet marketing companies are now teaming up with websites so the websites to their dirty work for them and you end up getting tracked anyway -- but with much higher certainty as to who you are. That means that now, yes, logins are more hostile.
The web continues to get smaller and smaller.