I'm actually glad to hear that. To be honest I haven't really seen much of the actual toxic stuff. I've just seen a lot of people being positive about themselves and their bodies - and unfortunately this gets a LOT of people really upset, simply the idea that somebody can feel beautiful at, say, 250 lbs. and can even go outside and enjoy themselves instead of having to be a shut-in out of sheer shame.
Hold on to your hats, I'm about to get all feminist on y'all: I think a lot of this movement that may be missed on some people who are against it is how gendered it is. To put it simply, girls get a hell of a lot more flak than guys do when it comes to being overweight. You can do your own googling on this point, but it is, quite honestly, a thing. And while dudes are encouraged to be fit - to be muscley, whatever - girls... aren't. The thin that women are pressured to be is overwhelmingly, well, unhealthy.
This movement is also really a backlash to the expectation that if you're fat, you've got to be dieting. And a lot of the time, that diet is NOT healthy. Unfortunately there are a lot of diets that are basically disordered eating with a veil of pseudoscience in order to make it conventionally acceptable. If you told somebody that you expected their entire life to be centered around food, and especially denying themselves food, you'd think that's a little strange, right? But that's often what people expect you to do if you're fat. (Or even just not as thin as a movie star!)
So there are going to be people that take it the other way. But before you jump on them sneering in disgust, spare a thought for why they're so frustrated. They have a lot of good reasons to be so. The opposite of a mistake often ends up another mistake, of course, but the things people are aggravated with are pretty legit. The fact that we're even here having to go back and forth is kind of depressing in and of itself.
If you think the fat acceptance movement is too aggressive or strident, take a second to think about why they feel they have to be that way. Stand in the other person's shoes for a little bit. You might figure out that what comes across as aggressiveness to you is actually legitimate frustration from people who have a lot to be angry about.
I can tell you that after being told all my life that I was too fat, too ugly, and too big to just about be fully human, having a voice go "hey, you can love yourself! you can go out in that cute retro-style dress and red lipstick and kill it if you want! you can take care of yourself because you are valued!" is really, really, REALLY life-changing. And it is really, really, REALLY a fantastic thing.