I think if one just gives everyone a thumbs up it becomes meaning less. A great answer deserves a thumbs, i can admit sometimes i forget to select the thumbs up when i read a great answer but not on purpose. Personally i would rather get no thumbs up then one given just because!!
I hear you Jorg I give thumbs up because all, MOST, answers are interesting and I appreciate the effort made to answer

Cheers Kev!