We spent a year making absolutely sure it is scalable so I would be very interested to know why you think it isn't.  Did you see that the on chain spaces are limited to 3600 per year and subspaces can be scaled off chain to billions

ca98am79

Coinosphere

bitcoin

Spaces Protocol: Scalable & Permissionless Bitcoin Identities

This type of solution is almost as old as Bitcoin. In the end, anything that requires on chain human readable identities is not going to work. It's unattainable and absolutely should not have the word scalable in the name. 