Theres a lot of value in the ecosystem through the asset store, that allows yoi to get up and running much more quickly than if you had to built subsystems from scratch (i.e. You can buy a good water package for <100 usd, whereas implementing state of the art would probably take you at least two months of dev time).

Additionally, from theres lots of educational resources, that might be harder to find for smaller engines

On the other hand, unity has a habit of shooting itself in the foot with incredibly messy and poor documentation, fragmented and duplicated functionality across multiple implementations (theres a common refrain in the unity community that every system in unity is either in beta or deprecated), so an engine that can provide an easier onboarding / dev experience could definitely compete there.

The main benefit of Unity over all other engines (from my perspective, anyways) is the large amount of skilled developers trained in it. If studios and devs start abandoning it, there goes your value proposal.