As you’ve noted there’s currently no way to hide drag and drop email templates nor organize them into folders. All we can do is create/upvote/comment on Ideas posts about this and hope that HubSpot implements it.
I see there’s currently already an Ideas post about it (maybe what you’re referring to as information from 2020?) . Having only 4 upvotes and no comments it’s likely not to be seen by the developers (but they’re even less likely to see posts outside of the Ideas forum). You could upvote it and leave a comment to try and give it some traction.