The known local fireteam issue has been since update 2.3.1.1 that was released on 7/28/16. It has not been around since 2014. The problem only affects some router models/brands, mainly cheap ones provided by ISPs and seems to stem from how they handle upnp. If you had issues before that update with joining a local fireteam it was a configuration issue on your end. That being said it has been almost a year now since the problem appeared and it should have been fixed a long time ago. I think the problem is they have been dumping most of their resources into D2 and only have a skeleton crew working on D1 issues. Game breaking issues get attention first and this is not a game breaking issue. It sucks that some can't play with local fireteam members but you can still play without them and it doesn't change the play of the game so it isn't considered game breaking. Things that affect game play get attention first. The second part of it is the problem is complicated and not easily figured out and solved, which is being made worse by the fact that a skeleton crew is working on current issues. They are working on it and they have attempted to apply fixes a few times but nothing has been a true fix yet.