About 70% of my group do, it spreads like a virus imo – the first guy in our group started using it because his road riding group did, once we started seeing it on FB a couple more of us started using it and it spread throughout the group, I think it will continue to grow amongst MTBers, even though, deep-down I think it’s fairly bloody useless off-road.
There are sections in my local wood that are 8sec long, it was 12sec but a couple of guy sniffed an easy KOM and started throwing themselves at it – there’s about 7 of them sharing it now, there is no way on earth that GPS is accurate enough to fairly judge a 40m / 8 second section off trail.
BUT, Strava has given me something I like, some of the easier / shorter loops at the trail centres have full-trail sections which are fun to race (for me) 30 min Blue Scar dashes and 45 min Verderer’s Trail rides are great fun for an old tubber like me.