Lots of eMTB's about at trail centres. 'Most' riders are fairly fit, but use it to kill the climbs in much less time, so get in more circuits at a trail centre, or cover further distances in a set time. I'd say an eMTB can climb almost twice as fast on a tricky climb, but the rider still has to work hard.
I ride with a group occasionally and one older chap switched betwen his normal hardtail or eMTB depending upon how hard the ride is going to be. I can easily keep up with him on his eMTB, but I suspect he'd be lagging behind the group if it was a hard ride and he was on his 'normal' bike.
The only ones that annoy me are the electric MX type bikes at trail centres, and the idiots that don't let you know they want to pass, but that's down to the ignorant rider.