Hello! I use three platforms on a daily basis. I vastly prefer my apps to be reasonably consistent with themselves rather than trying too hard to adhere to the platform.

My wife is on two. Most of my friends are on either two or three. In fact, I'm pretty sure my parents and a few coworkers are the only people I know who are exclusively on one platform.

Many (most?) people don't have a clue as to what the particulars of any given platform even are. They know how to get around in each app they use, and maybe the web browser, and that's it. Lots of gestures go completely unused.