I think "speed up Wayland development" isn't quite right, tho it will probably feel that way to end user. It's about getting experimental protocols into the hands of users in a formalized manner while the stable protocol is still being forged. This already exists in certain forms e.g. HDR support being added before the protocol is finalized, but having a more formalized system is probably pretty helpful for interoperability, e.g. apps having to work with different DE's.

My biggest is concern is whether there's a possibility this will actually slow down Wayland development by pulling attention away from the stable Wayland protocols in favor of Frog Protocols. But hopefully the quicker real world usage of the new protocols will bring more benefits than the potential downside.