Can't link Mojang account to Twitch

The Twitch broadcast button feature that was directly in the game was removed after MineCraft 1.8 around July 2015, in the past, this feature allowed you to Stream, manage your mic, and put Twitch chat into your in-game chat.

However after the feature was removed if you went back to older updates that still had this feature, then all you get is an error message saying that you need to merge your Mojang account with your Twitch account (even if you actually did).

The service that you're trying to use is discontinued, and you would need to broadcast MineCraft on Twitch the same way that you would most other games.

Here's an AntVenom video that mentions what I've mentioned on here (1:17-2:38):