The Minecraft you know and love is a
fantastic game, especially for kids. Top 10 all time, IMO, in terms of creativity and education and development. And you can easily set up a personal friends and family server/realm, and there are tons of free mods and maps.
The problem is that malicious actors can build Roblox in anything. It's not hard to get kids hooked and begging their parents for lucrative in-game gambling currency.