Diplomatic conflicts, provocations and disputes between Houses are normal and should be encouraged. It brings stuff to talk about inRP and stuff to do. Each House has its own interests and it rarely benefits other Houses.
That being said, open total wars between Houses aren't logical as all of them struggle to maintain peace & order even when all their armed forces are at home and dedicated to it. Because once they lose a portion of their navies and police forces, local unlawfuls will seize the opportunity to push their agendas when their House is weakened and distracted. And we're not even talking about extremely dangerous entities like the Corsairs or the Outcasts, both of which are basically preying on Houses according to their long-term goals.
So no, the wars between Houses is something neither of them truly wants as it's very, very dangerous for them even if they manage to win.
If this were real life, I agree completely with you. Conflicts, especially between houses, should be rare. However, this is a video game designed around economy and combat. Realism has already been reduced for the sake of entertainment (not necessarily a bad thing), but this community has a problem of finding that line between rational RP and entertainment.
That's not necessarily an answer to your post nor do I have an answer to this dilemma. It is a question that, from what I've seen, this community has never figure out so far.
It ain't about what you are capable of, it's about what you're willing to do.
