less appealing to who? Lots of 13 year olds learned to code by writing minecraft mods so it can't be that hard. You also get the benefit & satisfaction of it actually being in Minecraft—yes, they are both very similar games where you explore and place blocks in a procedurally generated world, but it really does matter. I can't really explain why if you don't get it but it's evident people do care even when they know about Minetest.

IMHO, "actually in Minecraft" is roughly akin to "my shoes are actually Nike".

That said, I never had any interest in playing on a server that was populated by anyone but my small circle of friends.

Now my kids are growing up doing the same which I find great because I know exactly with whom they are interacting and have no worries about it.

It's much more appealing because it has a much more vibrant modding community.

Community can go a long way towards compensating for worse technology, yeah.

Community is the entire goal. The technology just has to meet some minimum threshold. You know any 13 year olds playing Minetest?

My kids are younger than that and play Minetest/Luanti all the time. They are well aware of Minecraft but are completely engrossed by the modding first approach of Luanti.

I don't know any 13-year-olds, but I hear that a lot of them do play Minetest.