So most casual mobile gamers are true gamers because they don't care about graphics, framesper second and AAA games.
Casuals have always been the true gamers because they just love to play their game. They do not get caught up in platform wars, graphics, gameplay, physics, animation you name it. if its fun for them, they care less for all the other trappings.
I on the other hand cannot be measured by someone else definition of a true gamer. I love graphics, physics, animation 60FPS 4k and all those trappings. I want it all in my games including gameplay that interest me. I will also play a game on any system I have as long as i believe its the best version.
At the end of the day, I can be as casual as I want to, hardcore, old school millennial you name it. It varies from minute to minute, hour or days or weeks depending on my mood. I play games that interest me and that's pretty much where it begins and ends.