'Ok thanks' is two words long, it's adding nothing to the discussion, nor is it important to add. All it does is adding that one point (or two points, if it's a comment) to your AP count, and perhaps please those few people that really need to be thanked for their help. You gain points from posting and commenting, thus you can't just go about writing whatever you like, if we want to keep the community at least slightly organised. Write a good, long post, include your opinions and the like, and if you feel the need to thank someone, do so once, possibly on their profile, and consider yourself good. Or at least write more than just "Ok thanks".
If it was a game comment, it would be somewhat rude to write that little. "Good game" is an example of that. It might be a positive comment, but it adds nothing to anything besides your own AP count. The game developer can conclude they have made a good game, but not why, what has been good, what they should do next time they make a game and so on, so forth, and other users can conclude you think it's a good game, but not why you think so and if they would think the same after they have played the game, since there is no usable information in that comment.
i get what you mean because whenever i go on a game and look at the comments i see stuff like ggod game and good one and funny and lol and stuff like that and usually i try to be explanatory on game comments thank you