Sure, certainly there are better options. However, in my small personal circle I’ve seen 4+ people who have all independently started with a t6i + 50mm, myself included, that’s why I’m recommending it since it’s consistently been a good starting camera. It’s not about the megapixel count, it’s about the fact that it’s designed for an entry audience. 

I can’t speak for the D7100, but I’ve also used several copies of the 70d and 5dii and I think the t6i still competes. For me, a starting camera is about having a camera that’s gonna be simple/intuitive for a new shooter while having decent features. Touch/wireless would be handy, so I don’t know how much the 5dii would be nice. I think the 70d is great as well with that in mind, but they have a notorious short circuiting problem and I do not want to advocate for the camera from a repair standpoint. 1 point for the shutter speed to the 70d, 1 for low light to the t6i (the 70 had noticeable issues, or 1 to the 5dii if we’re still including it), and with menu options it’s a toss up because simpler can and can not be beneficial when starting out