It's not really a technical difficulty, aside from the fact that the unifi controller works really badly on macos. (also, I specialize in infrastructure, so the LAMP stack isn't an issue)

I just find it impracticable to have to maintain a dedicated machine (or VM, or whatever it is) just to configure those routers.

Now, however, I realize that this is because my current office only has about 4 of those and we're a 70 people company. I imagine it starts making a lot more sense once you start handling a few dozen of wifi routers.

So I guess the overhead of using Unifi at a small company might not be worth it, but, passed a certain amount of routers I can understand the overhead is lessened.