From experience with GitHub issues, I have a feeling that "+1"/"-1" responses might become a common thing on this board. I think it would be a good idea to figure out whether these kinds of replies are something we want (I stand on the side of not wanting replies like these, fwiw), and if it is not, whether there are other mechanisms that could better represent what those replies are meant to say.
A quick google search led me to this plugin: GitHub - gdpelican/retort: A reactions plugin for Discourse which replicates GitHub/Slack style emoji reactions. While I don't know whether this plugin is good, I think emoji reactions would be a good solution to this, giving people the possibility to express support etc without spamming the thread.