ZigBee devices are really nice because they are low energy, easy to set up and don’t add extra strain on your wifi access point(s). The battery operated ones last for months to years on a small button cell battery and most plug-in/wired ones act as repeaters. Also, a lot Wi-Fi devices are cloud based or require flashing to make them completely local. With ZigBee or even Zwave you are certain they have no internet access and cannot phone home without you having to put any precautions in place.
ZigBee devices are really nice because they are low energy, easy to set up and don’t add extra strain on your wifi access point(s). The battery operated ones last for months to years on a small button cell battery and most plug-in/wired ones act as repeaters. Also, a lot Wi-Fi devices are cloud based or require flashing to make them completely local. With ZigBee or even Zwave you are certain they have no internet access and cannot phone home without you having to put any precautions in place.