They were breaking the studio rules for years now and I just did a clean up. They were all trashed for either "having only 1 member inside them" or for "not releasing a single submission since their creation".
So no, I haven't trashed them just so. There were valid reasons support by the site rules. Also, the trash reason is NOT provided in the event log which is a bug that I have reported here.
In other words, you don't need to teach me what to do.