My impression is that Matter over Wi-Fi is the de facto standard for new smart home devices and Matter over Thread is really only a thing for compatibility with legacy Thread-only devices that got a software update after Matter over Thread became a thing.
That’s not the case at all. Matter over thread is newer. The latest range of ikea smart home stuff is all thread.
Thread has the advantage of consuming very low power so battery powered sensors and remotes can run for years. Wifi is only used because it doesn’t require buying a thread border router.