This was a problem even back when Gaim (now Pidgin) was at peak popularity. I used to be a dev on the team, and we had our accounts banned all the time. Some o

This was a problem even back when Gaim (now Pidgin) was at peak popularity. I used to be a dev on the team, and we had our accounts banned all the time. Some of the IM services didn't mind us being there (MSN seemed more than fine with it, and we reportedly had fans within the team there, though future protocol versions made it harder for us to figure out). Yahoo wanted us off and did everything they could to keep us from connecting. Changing auth schemes to increasingly-elaborate obfuscated methods, at one point throwing pages of what looked like equations at us. AIM would have been fine with us if we had used TOC (their open source protocol), but OSCAR is where all the features were at. They didn't outright ban clients, but my understanding is that their lawyers were involved at one point (though I think mainly due to the name "GAIM"). But you're right, they are removing third-party clients more. And fewer protocols are unencrypted plain text, which makes it harder as well. Still, work continues.