I don't think it's quite a titanic enough endeavour to put slow in quotes. It's been in development for 16 years and only got a stable support for screenshots a few months ago. Does drag and drop work yet?

IMO at this point it is reasonable to say that the idea of having a shared protocol and then making every desktop environment implement the entire display server was not a good one. The Linux community does not have enough manpower to make that work well.