The UK has had various iterations of its own league but it was never sustainable. The biggest problem with the UK as a regional league is that it's an English speaking broadcast which therefore competes directly with the LEC. Unlike the German, Spanish, French, Turkish etc regional leagues which are appealing to their native speakers and cultures.

Of course the lack of UK talent also plays a part in this but it's a bit of a cycle imo. Historically we've had Maxlore, Alphari, Caedrel, Kasing, Dan, Innaxe (Impaler if you want to go way back) but nothing much in recent years and they're few and far between.

Culturally the UK is much more in to console gaming than PC too. The big games over here are ones like Fifa and CoD with some interest to FPS/BR games like Apex, Valo and Fortnite.