Yeah, this is pretty dumb. If they're not going to implement a way for users to add games they've bought to their library like any modern launcher should do in 2022, then people are going to use scripts to do so which will probably hammer their servers even harder.
Just the fact that they're not automatically added when you buy it under your account doesn't make sense. And what is a "standard" library size anyways? They can't sell bundles with literally hundreds of games and then say our library sizes aren't "normal" when they're the ones that facilitated it in the first place!
Have you seen what they do if you complain about getting spam related to things you add to your library, and try to blame on using a script like this?
https://itch.io/t/1856548/how-do-i-turn-off-email-notifications-for-games-i-have...
Fact is, script or not, if you add things you buy to your library, expect to get spam that you have to disable one at a time. And you can only do so via the first spam you get for each item. You can't disable all these emails in one go; there's no setting on the site to do so. You have to click an unsubscribe link from each individual email.
Script has nothing to do with it. Simply having the items in your library will do it. It's not stopping them from blaming the script, though!