Okay, you name two and I can accept that as true. But we're still two hundred eight away from two hundred ten.
The real problem with this subject is that so many religious splinter groups call themselves what they are not. Example: You describe "American Baptist" but nothing about them is Baptist except the name they have chosen and that doesn't make them Baptist does it?
I mean a name is just a name, it doesn't mean anything if that's not what it is. I grew up in a Southern Baptist church and never even heard of "American Baptist" before now. Those people could just as well call themselves Methodist or Presbyterian but, if that group's doctrine is not the core of what they teach, it's not what they are!
There are several legitimate groups sailing under the name of Baptist but it's by no means as many groups as what you've read; I could just as well call myself "handsome" (and even believe it!) but it would be a lie because that's not what I am. Ditto, by your description,
American Baptists are NOT Baptist and I suspect that truth applies to the vast majority of those two hundred ten groups who claim to be Baptist!
That extends to other groups as well. I once read a long list of religious groups professing to be some form of Catholic but, in fairness, most of them really aren't Catholic at all (meaning they're much weirder than the real thing).