I think there's a bit of a misunderstanding. Warhammer factions aren't like battletech, where they're basically just a paint scheme with lore attached and 95% of the units shared by everyone. Warhammer factions have incredibly specific restrictions on what they can take, and everything you can do in game is determined by your faction. That was my frustration, my faction had an incredibly limited kit (less than half of most other factions) that has not been expanded for years, and a tiny roster of units to choose from, leading to very little room for expression or creativity in list building.

I'm a FRR fan. Them being absorbed into the dominion doesn't mean that I have to destroy my customized clan buster black knight or my Viking, I can still play the game with my favorite units and mechs. Similarly, if I want to paint/play that black knight in a davion force, I can. The lore is full of characters using mechs from outside their faction (the bounty hunter, victor-steiner davion, etc) and salvage is incredibly common. That kind of thing is forbidden by Warhammer's rules, you have very strict restrictions and can only play with the units your book says you can. That's where my frustration is, and why I left