I mean, the obvious thing here is that “it just works” compared to flashing (and knowing how to flash) custom firmware onto devices. In my mind there are two big things that Matter has going for it:
- Local-only support. If a device supports Matter it needs to be fully controllable locally per the specification.
- Thread support. All the perks of zigbee and z-wave with the benefits of a much more reliable and robust network thanks to its mesh design. Every Matter device can act as a relay for any other Matter device. The only thing that needs to talk to anything over the LAN (or internet) is a border router.
Those two things aside, Matter is open source. It was formerly ProjectCHIP. So, if the device has the correct hardware to support Matter (not all current IoT devices have the necessary hardware) in theory open source firmware for those devices should be easier to develop.