I don't think a DM will go entirely against their players' wishes, but I could easily see a DM and 2 players deciding they can 'work on' the rest of the group. So you could lose 100% of your users by pissing off the wrong 33%. Or 50% for pissing off 1/6th of your users. Which still supports the road trip etiquette of "don't piss off the driver."
Even that understates the situation, I think. Most players I know just aren't that particular about what system they play. (Sometimes they are particular about what system they don't play.) So if the DM says "I'm going to run the next campaign in Pathfinder", their players will shrug and look up Pathfinder character options. The more invested players might have more of a "cool, I've been meaning to give that a try" response. I don't know anyone personally who would fight against such a thing or quit the group because they only want to play D&D 5e.
As a DM, I'm partial to 5e because I already know it inside and out, so I can forget about the mechanics and just focus on the story. But aside from the sheer volume of official and "D&D compatible" material, I don't think it has anything going for it that other systems lack.
