I think Roblox is a cool platform.

(I get it, there's a lot of articles about it is bad, I've read them, I'm not convinced they're potentially worse than any other platform)

The platform is very fast performance wise. It's available everywhere and plays well on all sorts of devices. The friction to create content / play very low. The ability for the community to iterate through ideas that you wouldn't find anywhere else seems infinite.

Even my older kids who I would have thought aged out of Roblox by now return to it fairly often.

Every other platform just can't match the low friction, variety, and speed of Roblox. There are advantages of other platforms, but the ease of entry on Roblox seems to be the big deal.