That's something we can all agree on, but then why bring quantity into the discussion? I prefer lots of useful comments over few useful comments.
If 10% of the functions are commented, I will assume that those 10% are more important or have more error prone or dangerous usages. If every function has a boilerplate comment, I lose that information.
I also think that if people are in the habit of having to comment it makes them more likely to document things like expected values of the input, what the return could be expected to be, and if there are any caveats.