I should've clarified hardware as a "product" not hardware support. If we're looking at Intel Wireless Adapters for instance (Windows 10) only a will support it and so on. https://www.intel.com/content/www/us/en/support/articles/000054783/network-and-i-o/wireless-networking.html
You don't need to convince me about the necessity of WPA3 support, I've been using it wherever I can for quite a while already. However to use WPA3 exclusively, without WPA2 fallback or alternative, you need a quite modern and highend network, everywhere - and all the IoT/ smarthome stuff usually can't do WPA3 at all.
For most users with a heterogeneous and organically grown network of devices, it will take quite a while for the WPA2-only devices to be updated or replaced - even more so, if they don't start making it a must-have feature for all new purchases now (and no, none of the esp8266/ esp32 based IoT/ smarthome stuff will support it for quite some time to come). Even the highend android 10/ iOS devices claiming to support WPA3 now still do have problems actually using it (interoperability is still largely hit and miss, especially for mixed mode).