Hi, yes I have heard this many times. I do think some people have severe autism and some people have autism and severe ld.
I do think that some people with autism who are advocates or autism self advocates do other this part of the autism community for a few reasons:-
It goes against their narrative especially where that narrative is of neurotribes.
It shows autism at it's worst and not the Dan Akroyd etc al successful and flourishing type.
It is seen as diminishing their needs (I believe aside from the Hitler link, part of the reason the dxs were merged was due to the way the non classical autism was seen as milder and therefore not worthy of investment, funding or services).
I read a decent article about it some time ago, I'll try to find it.
We had an inde ep/ cp (very well known and highly regarded) assess ds for his transition to high school (tribunal over provision) we outright asked about ld. He doesn't have ld but he is impacted severly by the various subsets that he was assessed under. A formal ld dx can't be given likewise a iq value couldn't be made (although if it was ot would still be low but as the test is developed for nt people he is being measured in a way which isn't fair). We were categorically told he doesn't have learning disability so I won't refer to him as having that. His autism dx does refer to severe autism though so I'm comfortable using that as a descriptor.
Ds has limited verbal communication skills, has and does use aac etc. He was non verbal completely however he has always been hyperlexic even when non verbal and knows nouns in many languages. These aren't useful skills he doesn't understand what he reads. He could be reading a telephone book or directions or a letter but he wouldn't understand it or act on it. In terms of the other languages he can't use them in any meaningful way, I wish he could. I'd learn any language to baable to know what's he's thinking or wants to communicate. Imagine a teenager randomly saying house in Russion followed by tree in Spanish while sat in the lounge bit cannot answer if he's hurt, if he's hungry, if he needs anything (although we know how to read him). He can learn clearly but on his terms and his interests and can't apply that or rarely applies it. He likes patterns and repeated patterns so alphabets and numbers. He can count and uses that regulate but couldn't use it to time, play hide and seek or do math. He knows the alphabet order of letters but can't write or type a basic letter but can retype something he would use to regulate incredibly quickly (like ecolelia but via keyboard without relevance although we always assume competence so across on it, talk about, question it, get it etc). I dont really want to discuss hygiene etc as it isn't needed/ appropriate but you can guess.
Ds also regressed when he was a toddler- he lost all his learnt skills to that point and the few words he had more or less overnight. It was awful. He was just gone, his personality everything.
Our older son is very bright and will likely get 4a*'s in maths, further maths, chemistry and physics at alevel (no dx or signs of autism, no mh, just a norm teenager). We often wonder how our youngest would be and suspect he would be similar without his autism.
I know there is a least one ep on here so to give an idea his newsy ii scaled score was 1,his wisc-5 subsets were all extremely low (one less than 0.1) and one was very low (fluid reasoning was a 9). With a statement about ld not being able to be diagnosed and the components of his autism.
I think both mh and ld should be talked about as separate to autism while I recognise the impact they have on each other. You can have any of them as a stand alone dx or all of them and they do impact on presentation. It would be clearer all around if severe autism had a set meaning and not severe mh or severe ld.
I hope I've answered that well enough. I'm happy to engage and discuss respectfully but don't want to go down the road that these threads often do.