Glad I decided to not use WP

Themes and plugins do have a bit of "shelf space"-like pressure; the WP upgrade treadmill. WordPress releases frequent updates and version upgrades. Themes and plugins have to test against the new versions, at least, and mark themselves compatible.

A plugin that stops doing that will not show as compatible with the current version in listings, and many security plugins will warn users of those plugins.

So makers of those plugins must invest some amount of time on an ongoing basis.