I completely appreciate the frustration, and the quality issues of strava's routing feature is a whole other thing... in this park for example, unless a trails is explicitly marked as foot traffic only, all trails are understood to be accessible to foot, bicycle, and horse. Trail visibility, or mtb:scale can better inform on what to expect for a given section. 

As far as fords are concerned, water levels change, rocks move or get moved around, etc.

I've done my share of hike-a-bike in patapsco when goofing around on a gravel bike a few years ago. 

Why one of the ways was marked skateboard=yes, that needs/needed to be cleand up.

I hope this clears things up for you.