I couldn't agree with you more, if you want a real fitness tracker/sports watch, smart watches just don't cut the mustard (I'll caveat this with I have no experience of recent smart watches that focus more on sports such as the Samsung Ultra series).
I had really bad experiences trying to get basic sports functionality on WearOS, such as the ability to get a route on the watch I could follow. Sure there were third party apps, but these were unstable, resulting in me losing my bearings during a run in France one time. Garmin on the other hand I can either design a run on their Connect platform, or tell the watch a distance I want to run and in which direction and it'll auto generate a course for me to follow.