So you think it should be limited...why?
I think (and I could be wrong, I don't read minds, yet) he's thinking along the same lines that I am.
That the romance across the companions being universal is more a matter of Bethesda being lazy than crafting an actual good system of romance.
It might sound hard to have every humanoid companion be able to fall in love with the player, but that's actually the easiest route to take.
No real differentiation, no having to undertake any specific actions to get them to fall in love with you.
Just a few lines of flirting and they're ready to jump your bones.
It's basically how it worked in Skyrim.
All of the marriageable characters were exactly the same in performance and behavior.
The only difference was the voice acting.
So instead of having the characters be actual characters, they're basically just going to end up props for the player to fiddle around with.