Strava doesn't have complete coverage, especially on newer trails, but more importantly: doing the trace via Street Complete attaches it to an OSM note with an optional (but encouraged) photo. This additional context makes it a lot more useful for editors than an ordinary trace, which can just as easily be an actual trail, a desire path, or someone deciding to improvise a shortcut through some brush. Even if the note just contains the word "trail", that helps us (though more detail is greatly appreciated, of course).