A lot of weird gender and sexual hangups are all mixed up together in our classic picture of the drow -- there is, as you mentioned, a rather improbable amount of whips and chains. Is their villainous matriarchy specifically an issue, though? Like, imagine the most matriarchal society in D&D not being villains. Imagine the gnomes or whatever are said to have these strong attitudes about gender superiority, but are presented as "good" or at least respectable. That doesn't really work either, right?
I don't agree. You've made this claim before, but it's wholly unconvincing to me, because D&D literally only ever specifies when something is a matriarchy, never when it's a patriarchy, even when it is obviously a patriarchy. If you have a society, and every leader we hear about is male, and they have only male combatants, and so on, it's pretty obvious, I would argue, that that's a patriarchy.
And yet cultures which are presented as unnamed-patriarchies are presented positively in D&D. Dwarves have frequently been presented as having solely male leadership, particularly in earlier editions, but it's almost never spelled out. Instead we just see all Dwarvish leadership is male. You see the same with other cultures - we'll see six or a dozen or even more leaders, and every single one of them will be male, or the only female one will have an actual explanation of why she's even there (usually she's someone's only child, or widow - which were the typical RL historical explanations for women being leaders in otherwise patriarchal societies) - an explanation absent for all the male ones.
You can't go on pretending that, just because people aren't naming patriarchies, patriarchies, they're not patriarchies. It's like our own society - it's been a patriarchy for thousands of years. Did it get called that much before the 19th and 20th centuries? No. Because it was just "how things were". And D&D has done the same, pretty consistently, for decades.
Even societies which are definitely egalitarian do tend to get called out as such in D&D, again, especially in earlier editions. Which again suggest that patriarchy is the default assumption, and it's only worth noting if it's different from that. I'm not going to bore us by listing all the other things in life which can work this way, but you know perfectly well, because you live in the world, that something can be a thing without being named as such, and pretending that because it hasn't been, it isn't, is pffff disingenuous at best.
I will note that when a demihuman race is closely examined, even if literally every ruler we've ever seen has been male, they tend to be suddenly "discovered" to be egalitarian, or have some kind of system that's sexist, but somehow gives both genders equal power (or males more, but not by a vast margin - still that is somewhat patriarchal, even though they'll never call it that).
And yes, it definitely is a problem, because it explicitly links matriarchy and being outright villainous. Being matriarchal or patriarchal doesn't make you "D&D Evil" (unless you want to label literally all your ancestors for hundreds or thousands of years, and the culture you live in as "D&D Evil", which is like, a bold move I would say - not necessarily wrong - but bold!). You could certainly have an LN culture which was Patriarchal. They might be prats, jerks, losers, but they don't need to be Evil with a capital E. Likewise Matriarchies. They're less likely to be Good (given the inherent link to equality), barring some wacky examples where they just choose women as leaders not because they're "superior" in some general way, but because the culture believes something else makes it sensible, but even that's not impossible. So again yes, making them not only evil but Super Duper Nuclear Grade Atomic Evil, the Evilest of the Evil, and as you do not, dragging in a bunch of other creepy junk about cruelty and whips and chains, is deeply problematic.