No forum can be all things to all people. There are literally dozens of options available to folks who prefer different moderation styles. While every one on staff here certainly wants everybody to participate in and enjoy this forum, we simply can't make everybody happy.
As other have mentioned, specific answer would require specific examples. We don't generally close a thread that "gets a little off-topic", depending on how one might define "little" and sometimes what the topic might be. As an example, in the hunting forum, there was a recent thread that started out asking about shooting hogs with a bow and turned into a discussion of broadheads and accuracy. Technically, that's "off-topic" but it wasn't closed.
Also, keep in mind what JohnKSa said. If staff deletes a post, general membership will have no idea that it ever existed unless they saw it before it was deleted. There have been threads that were closed that had a dozen or more nasty posts deleted. What remains appears to be civil and on-topic but that doesn't mean it WAS when the missing parts were there.
Still happily answering to the call-sign Peetza.
The problem, as you so eloquently put it, is choice.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.