Is this an autistic thing?

I think it just refers to solidarity here. You could always say ‘thank you for sharing”. (Full stop)

I think 'like' can be confusing and would like more options. To me like fits something like a lovely picture or other artwork for example. Perhaps agree would be a better thing, as if something is sad or negative ' like' doesn't seem right. 

I would say it could be. Over analysing and worrying about things like this, is an autism trait. I'm on another gaming forum and there's a hug button, probably be useful here too. But even though I still worry whether to do it for certain posts.