For me, the 2 main reasons I can see are:

1) removal of screenshots, that I should likely just put in /tmp instead (yeah, I *should* do that, and other adjustments, too)
2) removal of garbage programs leave behind, even in /tmp (yeah, I *should* find a way to remove /tmp stuff after some some duration...)
3) removal of cmake's or other toolis like this artifacts when stuff break
4) removal of temp files I write, often in my $HOME

Other than that... I don't know, it surprises me too.
Globally, I think my workflow is pretty inefficient, tbh.