Obviously it would be terrible if everyone posted 'I agree' comments, that's the point. Numbers show the viewers sentiment towards a comment without clogging the thread.
It is self-evidently true that removing visible comment scores mostly removes methods for trivially measuring "viewer sentiment". It is the contention of those in support of non-visible comment scores that trivial measurement of viewer sentiment harms, rather than aids, discussion. You have made no argument against that point.
Trying to aid discussion by limiting information is fine, unless you happen to want that information.