There are several airlines who don’t have inter line arrangements in the traditional sense - Ryanair, easyJet, Wizz, Jet2 to name but a few. But their business models don’t need or want them - and easyJet chooses to do this via another means with its Worldwide programme.
The difference is that if you need them and want them, but don’t have them, it will impact performance. The only other airline I can think of which has none and in the same boat as Flybe is Eastern.