Once you introduce a rating system for what people think and say, it ain't "normal interaction" no more.
Think about it, it really is; in normal interaction, you also filter out the people and messages you don't like to hear or see - either by ignoring them or by the way your mind absorbs the information. We all do this, every day, both consciously and unconsciously. We even do most of this based on first impressions. On the internet, the tools you'd use in real life are not available, all you have is text, no verbal or non-verbal communication to convey how you feel about something/someone. A rating system based on a simple scale (1 - 5, effectively) can be a good substitute and definitely a better one than the rather rigid 'Like or Dislike'.
Also consider how people are using the 'Thanks/Like' functionality on this forum. Is it really to support the best/most informative posts, or is there a strong degree of bias in them? The bias is there and it shows because the range of options is extremely limited - you can either do nothing (ignore / be indifferent) or you can 'Like'. So we see tons of likes under prominent posters here under a comment that really makes very little sense or 'is a bit funny'. How does that help us today? I think you can explain that behaviour in two ways: either people just get personal, or people lack the right options to convey their thoughts. Regardless, they WILL voice their opinion and if they get tired of that or if they can't do it effectively, they will leave the forum or just not participate. And I believe that the aim of any forum management should be promoting the participation of all readers. With ratings, they can do that in a simple way without having to repeat what was said in a post before them. They can now express varying levels of agreement/disagreement based on a rating, making the post more prominent, and therefore implicitly also providing their opinion (without adding dozens of pages of 'the same' to a thread).
The benefits are obvious;
- less prominent / less attention for shit posts
- it no longer benefits anyone to repeat something posted by another person
- it promotes actually reading the topic
- it motivates to add useful information to a post, to make it worthwhile to rate and read
- users get their own tools to filter and see what they want to see, resulting in less annoyance over what other people type