Totally.

I guess the privacy advantage of a regular SIM is that as soon as you pop out the sim card out of your phone, towers can’t track you anymore.

With eSIMs on the other hand, I can never truly trust that an eSIM is de-activated? Feels like you actually just have a permanent sim card in your phone and your phone can just be tracked no matter the status of your eSIM. Or is this not technically possible?

For the known top trackers, it’s to have more control over nefarious users such as duped accounts, banned users and potential law enforcement trying to sign up. Sure it’s not a bulletproof solution to deal with bad actors but it’s still an effective way. You gotta remember that these trackers are free (yet private). The admins/operators don’t get paid, so last thing they want to do is waste time dealing with such users.

At the end of the day you still have to trust them with your real IP, but it’s mostly to protect themselves afaik. I obviously can’t speak for every tracker out there.