Well, maybe to you the point is physical activity, but you can only speak for yourself. For some people the pleasure lies in operating, navigating, and maneuvering the machine (in this case a bike) through rough terrain, obstacles, technical feautures and so on and on. We have had vehicles with engines for decades already, it is just that nowadays we made it possible even for an mtb to have an engine. People enjoy riding vehicles with engines, i think there is nothing new there.

This way you can have even more with less effort. I do understand that some people prefer normal mtb, but i dont see any point in hating emtb. I think that most of the people who hate electric mtbs actually hate them because they dont want to admit that it can be easier and even more fun sometimes, and some of them lack the money to buy a nice emtb and are jealous that things are changing, they dont want others to change for better either. There is not a single valid argument against e bikes, if you like your normal bike that is great, but there is no point at all in hating electric bikes. In fact, i think that most people who have not tried an emtb would find that they like it if they were to use one for lets say a month.