How does having a user account make you less free or infringe on your privacy?

Letting them correlate your access patterns certainly does reduce privacy.

Fun fact, you don't need user registration to do that.

But user registration makes it so much easier! Single identifier shared across all user's devices and browsers, and which survives reinstalls, cookie eraser plugins, and needa no GDPR notice - that's the best thing an advertizer can hope for.

Sure, but its a bad metric to decide what sites to use. The evil ones will still track you regardless, the non-evil won't regardless.

Usually registering an account also requires an email address. However, if definitely indicates wanting to track your use on their site.

If they don't say they value privacy and freedom, what are they?