And has a poorer range and penetration which ultimately makes it always “loose” the battle.
Check this nice write up on all the things necessary to maybe get a stable experience
But still you can not be sure if all advertised functions are also working. The limitations are mostly “visible” after purchase and can easily make automations unecessry unreliable like hygro/thermometer that are sending changes only every X minutes or motion sensors with a fixed cool down timer. Another topic alone are custom quirks to get functions working which often can be very time consuming.
Fromy experience the ZigBee network suffers the most with heavy streaming including devices dropping out of the mesh. On the other hand I never managed to satrate our 2.4Ghz - 600mbit WiFi link (would need a minimum of 12 parallel 8k streams ~50mbits) and even if I would expect everything to continue to work because from my mileage WiFi is (unlike zigbee) very robust even in heavy congested situations. Beside my streaming clients are using 5Ghz WiFi anyways…