I think Memes distract from the seriousness of a conversation. I see on Threads where somebody starts a conversation about something, and then is overwhelmed by meme responses. Yes, it's comical, and entertaining, but do they actually answer any questions? Yes a picture says a thousand words, but... sometimes those words are just as if the Tazmaininan Devil was uttering them.
Personally, I have a separate are reserved just for crap-posting and memes.
I think it depends on the forum and to some extent the area within the forum they are posted. If it's off-topic banter then fine if that's what floats your boat but if it's a serious discussion area or even even worse, a commercial support forum it really should be discouraged.
xenforo.com is one of the worst forums I've seen for allowing multiple memes to be posted in a customer support area.
Memes can help make discussions more fun and relatable, and they often get people engaged quickly. They also help build a shared culture in a community. However, if they’re overused, they can reduce meaningful discussion and turn conversations into quick reactions instead of thoughtful replies.
Memes seem to just breed more memes. We have a gif conversation thread where every reply is a gif. It's fun but for things like search engines I'm sure it's a nightmare.