My first MTB was in 1988. We were just glad to have a dirt bike with gears, as previously we had stripped down the old JCHiggins or Sears bikes and road them in the dirt.
Now, I am happy to have a XC bike.... and ride it on fireroads or trails, so it's the same for me....Don't really like single tracks... to many ticks. Let the young ones do this downhill stuff..... get a few broken bones and they will learn from doing. I consider anything off road as mountain biking... even riding gravel roads.... just use the MTB. Get out and see some good country!