No technical limitation, but the market demand just isn’t there yet. There were multiple issues with the initial thread implementation for matter, as you might have followed in the matter discussion thread in this forum. It’s really only been the last four or five months that those have been worked out, and it’s still not perfect when it comes to multiple thread networks in the same fabric.
Matter - smart home connectivity standard (formerly Project CHIP)
And from a general matter standpoint, the assumption has always been that Wi-Fi would be used for mains powered devices and thread for battery powered ones. That’s the direction most of the manufacturers have gone.
With the exception of the brand new inovelli white series, there are almost no thread switches for the US market either.
I don’t personally have a sense yet as to whether this device category will ever pick up. But they certainly aren’t here yet.