Minetest is pretty awesome but it has some harsh limitations like a -32k -> 32k block world size limit in all directions as well as not being world file compatible (i know that experimental converters exist but half the blocks never load in and these are as old as 1.2.5 blocks so no chance it will even attempt to work with 1.12.2 maps) so for someone trying to get close to vanilla, I still think reimplementations are the way to go.

The finite world is a problem in practice only for popular game servers. I think the base walking speed for characters is ~2m/s, so reaching the edge from origin would take at least 4 hours. Even free-falling from max altitude (10 m/s is the max speed IIRC) takes a while.

Moreover, the "finitude" of the world can be mitigated by the fact that Luanti also offers 64 km total vertically out-of-the-box; various mods use this space to create the equivalent of "dimensions". In practice, without tools that allow to dig ridiculously fast, supposedly realistic mountains (what can be realistic in a game where you can carry with you several trees, casually jump 1 m anyway and barely get a scratch from a 15 m fall?), planes, dragons or whatnot, a "troposphere" of 1 km is plenty, and would allow 128 64x64 km "dimensions".

That being said, and my own biases put aside, people outside of the Luanti core team are working on that [1]

[1] https://forum.luanti.org/viewtopic.php?t=9183