The Reno families started as raiders as did(likely) quite a few robber barons. I'd also say that personally I consider the BOS high tech raiders.
They started as mafia families in pre-War Reno. Then the nukes fell, local government eventually collapsed, and guess who was there to pick up the pieces?
The Brahmin barons also weren't raiders, they were farmers and caravaneers. Though as late as the FNV period they were hiring raiders as mercs to fight low-level internecine wars against each other.
It's not like a situation like NV, where House got tribals to LARP as gangsters.
I have to assume that most raiders either got with the times or got squashed. At this point, they've more likely evolved into regular criminal enterprises rather than packs of deranged murderers wandering around and causing havoc. Functional societies tend to react harshly to overt acts of anarchy and violence.
More like raiders got squashed, regular organised crime families took up their place.
As for the BoS, all of the moderate chapters were wiped out or suppressed in this universe
Who says the BoS moderates are all out of the picture?
Practically speaking the super-orthodox idiots aren't going to make it. Their governmental system is literally antiquated and highly inefficient compared to the more or less fully functional nation-states on either side of them.
The Brotherhood's best shot was to maintain their alliance with the NCR and accept their role as the junior partner in said alliance.
Even in a universe where things work out for them, the old Lyons faction is very likely to eventually win out since they actually try to adjust to the changing world rather than desperately attempting to force a misunderstood and outdated transitional ideology onto reality.
The Brotherhood were definitely heroes back in FO1 and FO2. And Lyons? Lyons had no wider vision beyond an incoherent idea of helping out wastelanders, which is all very well and all but isn't enough to found a polity on. Perhaps if his daughter had lived in canon she would have turned his vague concepts into something workable, but she didn't, so she didn't.
The later Brotherhood was always tragic due to how far they'd wandered from Maxson's original intent. In this world that tragedy has metastasized into, as you say, a polity of techno-barbarians.
Yep. Roger Maxson didn't want any of this, just like Aradesh didn't want the NCR to become an industrialised, always-on-war-footing, imperialist superpower.
In conclusion i see no reason whatsoever to believe the BOS is anti capitalist. Also it should noted that the E BOS are well heretic's. The way they operate and do things shouldn't be taken. As an example of any other BOS chapters operations.
You forget that for the BoS to allow a free market in the territory they administer would be (inevitably) to allow advanced technology to go out of their control.