This is a sensational exaggeration. Apple maps new trail feature only covers selective few national parks. Knowing apple nothing will be crowd sourced so it's really can't compete with most trail apps out there.
If anything it may drive engagement… many people will find AllTrails or Strava after hitting whatever arbitrary limits Apple places on the feature, as well as the normal Apple pattern of neglect.
Even marquee apps like fitness are very limited — Apple doesn’t provide great tools for runners, for example. Garmin does, and seems to be doing ok.