Not just storm water, but also things like maintenance of 'common areas', roads, and snow removal. Many small municipalities are budget strapped and don't want to be responsible for plowing/surfacing the new little 1/8 of a mile culdesac the developer created to build their 'neighborhood'.

In carving up the 5 acres the developer purchased, the 30 houses they squeezed in left some remainder that wasn't buildable or odd shaped, so this now becomes a lame 'park' or some other space that requires maintenance.

I read all my local municipal meeting minutes, and at least around here, permitting and ordinances control all the environmental/nuisance stuff, so I can't really explain why HOAs go beyond the collective expenses into the draconian rules.