The problem is more complicated and more interesting than this. You can have many innocent comments, none objectionable in its own right, that add up to a situation no one wants or enjoys. The issue isn't that the individual comments are bad; in principle they could add fun to an otherwise good and substantial site. But in practice you can't have a stable equilibrium that way: if you allow it, you end up with a snowball effect in which such comments take over and it's all downhill from there. Therefore we can't allow it. It isn't about being killjoys, but about protecting the viability of the site.