Signing up is one thing. Putting a product on the market that people will actually buy in quantity, that's a whole different can of worms.
Especially when you consider that the inexpensive WiFi devices that don't work worth a damn with HE, but do hit the three big checkmarks: "Works with an App on your smartphone", "Works with Alexa" and "Works with Google Home" have set the price bar pretty low.
That's the market they have to compete with, and it'll take some very aggressive pricing to muscle in on that turf.
We shall see. Bear in mind that the "Works with Alexa" and "Works with Google Home" cost a fair chunk of money as well. Tuya charges per each one for their rebadges for example. So no product you're buying, even the cheaper ones, is free of those costs. Matter it seems is purposed to replace some of those costs if the system works as advertised (remains to be seen).
Also, if you look over the pricing for certification (which isn't cheap either), per product is cheaper than even Wifi certifcation. Hopefully we'll continue to see products across the price spectrum with Matter, if they all come out at premium prices then I agree it won't get far.