The thumbs were added to provide feedback to posters when people couldn't be bothered typing. Much like you'd grimace, smile etc. We don't always need to talk to get our point across.

Due to the inventive nature of humans, it soon became a tool. Haters of a particular poster would then go on a binge of red-thumbing every post by a particular person. Childish yes, but .. it's what happened. And happened a lot.
So then we introduced ratios to combat this. We introduced limits. So then people go create extra logins to continue their red thumb fest. And before you know it, thumbing became a moderation task, and we're like .. "How did we get here?"
So.. we decided to remove red thumbs, and the results have been good.
However: this are still issues with particular members, and so today, we introduce the new "Hide Member" feature.
If someone really bothers you, you can hide their posts, and you'll not see their posts again. Only posts
by the user. If somebody quotes them, that post will still appear in your feed. To hide a member, view their profile and select "Hide". Easy.
It is saddening that we've had to add the feature, but .. such is the nature of things.
Enjoy..