I found some things wrong. Occasionally these were minor things that the authors corrected. Sometimes they were major problems, and I recommended that the paper be rejected because they were unfixable. In that case I'd usually see the same paper get published in a different journal later on.

So your conclusion should be: peer-reviewing is working, but some people are not using it right.

You then need to assess exactly what is this percentage of still being published despite having things wrong in it. If this percentage is small, peer-reviewing is still more profitable then no peer-reviewing at all (in which 100% of the bad papers are published).