The only reason is that there seems to be more “power” devices controlled via Zwave than Zigbee.
If you can find a Zigbee one, at the right price AND it’s supported in HE, then grab em 
Regarding WiFi v Zigbee/ Zwave there’s loads of threads on this forum, mostly pointing to the higher possibility of interference and lack of integration of WiFi products. I found this one Interesting
