Any developers that can make their own in-dev engines that work and are possible to handle on their own do have an advantage on flexibility and potentially optimization (if they do bother with that), but if that's not a viable option for economic or staff reasons, then managing with UE is the closest they can get to that. That said, I do hope that licensing issues don't get to cause any amount of bothersome issues later on, since there's one very, very particular and out there example but that's hard to forget if you remember it once:

Renderware games.

Ever since Electronic Arts gained the ownership of Renderware, it has left any game made in that engine legally stuck in limbo regarding ports (which might have as well been troublesome even with that considering the age of the engine now). While it is hard to imagine things becoming as obsolete at that rate of speed due to how techonologically ahead we are now in stuff and standardized code, yet you never know with compatibility if something brand new happens to come through.

But that's the worst case possible; UE is definitely a great tool in the best of hands, so on that matter it is up to the developers to use that at its best, in the same way that Unity and Godot can also do great things but can get a worse rep because of lesser-quality creations over accessibility from people in the internet (which shouldn't take away the power of these engines, as seen with what more notable works can offer).