Discourse does not have a like button. Discourse has a reputation system where users can advance to higher trust levels and take on certain moderator-level abilities, and the like button is an integral part of their reputation system. Discourse expects message boards to be largely self-moderated by the users. This entire system does not fit with the way that we have been operating for the last couple of decades, so we intentionally set the requirements for higher trust levels to be impossible for normal users to attain.
As @running_coach said, likes were enabled at first until we realized exactly how they factored into Discourse’s reputation system. Similarly, a lot of users managed to give themselves moderator powers, and, being the SDMB, they immediately abused the privilege and started doing all sorts of things that they weren’t supposed to do (changing other people’s user names, etc). Likes were disabled and a few other things were tweaked to keep users at non-moderator trust levels.
Discourse was a bit of a learning curve for all of us.
A lot of people want a like button here. Unfortunately, you can’t separate the like button from Discourse’s reputation system, so unless they change the software, we can’t use their like button here.