I think that was one of the ideas behind Lego Worlds, originally. It did end just as a sandbox, but I believe originally it was going to support scripting and sharing of games - with the idea being that Lego might pick up the most popular of them for standalone release.
Somewhere around the 2015, the beta releases dropped the capability. (Along with infinite landscape.)
There was some rumours about Blockland maybe threatening legal action if they kept it, but nothing concrete, so take it with a grain of salt.
I never heard of block land, I just looked it up, watched this YouTube video about abandoned multiplayer games https://m.youtube.com/watch?v=1FEW7gxci2Q . It was a bit sad to see it in such decline. It reminded me of a non commercialized version of Roblox.
Roblox does seem to be particularly bad at moderating it. For example, the Wikipedia section on Club Penguin's child safety concerns [0] makes it look like Disneyland compared to the reports I've read about Roblox.
If I remember a video I watched on the subject correctly, creating a safe space for kids on the internet was the explicit goal of Club Penguins. Good moderation was a selling point in a time when most parents wouldn't let their kids "surf the web" alone (rightly so...).
Now that kids spend almost more time before the screen than not, and that the Overton's window been shifted to a place where it has become acceptable to market digital casinos to kids, no one bothers with costly moderation anymore.
That allows chat. Can go the hearthstone model where all you can say is “hi” and “good job”. Letting randos talks just is going to lead to bad times w kids.
There used to be a blog where a developer who worked for Disney and their Toon Town MMO discussed the absurd difficulty of trying to keep young kids "safe" in an MMO.
The bottom line is this: If you give kids literally any way to communicate, they will use it to bully each other and destroy the "kid friendly" nature of the game. If you let kids place objects in the world, they will spell out their home address for a pedophile by dropping objects to create words and then build a giant penis next to it. If you give kids the ability to emit only a few specific pre-approved sentences as a "chat" feature, they will find a way to sext with it, and then tell a pedophile their specific location through an ad-hoc code involving character facing direction and specific sentences.
Kids are smart, and imaginative, and don't understand or respect the concept of "You aren't supposed to do that" and don't recognize the danger of telling strangers your home address (in as much as there is actual danger there, as "stranger danger" is massively overstated) and will utilize ANY possible signal channel to explore taboo topics in an environment that seems safe.
Like, people in the Wii days shared friend codes in multiplayer shooters that had zero chat by using gunshot decals to spell out friend codes one digit at a time!
Either don't make a game where strangers can interact in any way, or pay shitloads for aggressive moderation like disney did. Those are your two options.
Or just do what roblox does and let kids be found by literal pedophiles who then go on to sexually message them and just somehow not have parents freak the fuck out? Also you get to literally profit from the work of children. I guess the moral of the story is to sell your soul to the devil because he has great PR
I love this idea, imagine if Lego had an open game creation platform. So much potential for idea generation.