It's definitely more complex than being 'just' an issue of sexism (as if that wasn't bad enough), but that doesn't mean sexism isn't a part of it. I would argue that the problem is multifactorial (but not in the way the BPSers think!).
Hysteria and related concepts are inherently sexist, and I don't think we can easily deny that that influence still exerts an effect on diagnoses like ours. Sexism creates the language with which people frame our illness, even if that language is also directed at men. So while it appears we get a pretty equal treatment, that's only because the sexism now applies to everyone.
But that language is also classist and ableist, such as talk of 'strivers versus skivers', which paints many people with chronic and invisible illnesses as layabouts, scroungers, attention-seekers, etc. There are narratives about the 'deserving' and 'undeserving' poor: those of us who don't show easily categorised, objective illness are probably considered 'undeserving' by others (e.g., by a minority of medical staff who think we're wasting time and resources, by DWP staff and their contractors who think we don't deserve benefits, or by Daily Mail readers who think we're 'trying it on').
Then there's the idea of 'yuppie flu' striking down those who deign to do well. The term 'yuppie', in applying to the young, is rather like the disdain some publications have for students now. It's young people trying to better themselves that they don't seem to like, or young people who threaten the status quo with their 'soft' ideas such as staying in the EU or asking that their uni fees aren't used to pay people who speak hate.
Presumably, the problem with yuppies is that we're too ambitious and yet too soft to handle the pressure of that ambition, or that our ambition is somehow a kind of class treachery where we're trying to be 'above our station'. We don't know our place in society, ergo we're at fault for our illness.
ETA: Yes, some of these intersections actually contradict each other--but prejudice isn't usually rational!
I think in terms of day-to-day experiences, most of us will get pretty poor treatment. But I also think things like women having to have men present at consultations, in some circumstances, does highlight that everyday sexism worsens that experience in addition to the crappy treatment everyone gets.
Other things will increase the barriers to good healthcare too. For instance, I know a trans woman who was told her ME was 'merely' a manifestation of her 'gender dysphoria' and internalised hatred of her own body (I kid you not). That kind of attitude can make getting care harder, too. Another example might be the 'aggressive' black woman who gets labelled with borderline personality disorder for 'attention-seeking' behaviour (this happened to my friend, who was convinced she had ME and was merely pursuing specialist input to rule it out). She doesn't press things any more because black people are more likely to be sectioned and she's heard the horror stories.
As a man (a mixed race, gay man, mind you, but still a man), I think I've mostly had neutral to positive experiences (not always, though). The only person who really wound me up at the time was a doctor at the local CFS clinic. My GPs have been very supportive and helpful (though I usually book appointments with women for a reason).
I think we can't really talk about hysteria without talking about sexism. But I also think sexism against women impacts upon men too. Pragmatically, I also think the feminist focus sells more books. But I don't think it's a misrepresentation either. You could include racism, classism and ableism in that discussion too, mind you.
Now could a book about how ME affects men also sell well? Probably, and it would be an interesting read. I think part of the negative experience men with this illness have is that they're experiencing the sexism women face everyday, which they're not used to, and this heightens their distress at receiving crappy treatment. There are implications that we're 'less than men' or should 'toughen up', but those are pretty gendered concepts. It's all bundled up with the gender expectations of masculinity, too. This is why everyday sexism and gender stereotyping harms men too, even if it's usually overtly directed at women, because the assumption that 'feminine' = 'weak' cuts both ways so that 'weak' men are 'feminine' and therefore inferior. Note that early researchers on hysteria (and related concepts) in men noted that it affected husbands who were 'passive' to their wives.
tl;dr: I think you can argue that multiple forms of discrimination can be at play in both our medical encounters and the stigma we experience more widely. Focussing on one doesn't necessarily mean those other factors aren't also at play, though perhaps some factors get more airtime than others.
