Waaaay back when…I wanted to set up Yahoo in my mail apps and I wanted IMAP.
At the time the only way to do that was to go to the actual website and set up my location as Singapore. I have no idea if anything has changed since then, but I've not ever gone back and changed my location. I still have IMAP.
Only now, Yahoo is demanding app-specific passwords. I just set up my Yahoo account in Entourage 2008 a few weeks ago and it would not take my normal password. Had to go to my account on the website, generate an app-specific password and use that.
I don't know if any of this helps you, but I've had IMAP with Yahoo for years.