@BarryFromMars
The pieces work individually, but the power of the crystal is proportionate to its size. Sombra wanted the whole thing because he probably wanted to steal more than the right to legally govern a small town.
All ice is cold, but you need more ice to keep an icebox cold than you do to keep a glass of water cold, y’know
Part of the problem with writing for the pony universe is that the main characters are ridiculously powerful. Twilight can teleport and make force fields, Fluttershy basically owns the animal kingdom, Spike has the power of instant long-distance communication, and Princess Celestia often appears to just have “make things better” powers.
The world is full to the brim of magical objects and characters that could be used for innumerable solutions to a problem like this. Rather than spending half the comic time hurriedly explaining away why they don’t do X or Y, I opted to simply leave out elements of the world that I didn’t want to be bothered with. My hope is that the audience understands that if I don’t show a card first, I generally won’t be playing it later.
Unrelated, but I’d much prefer you didn’t make comments on Three Apples pages making fun of mentally handicapped people. I’m aware that I’m in no position to moderate these comments sections, but I allow Three Apples to be ed to Derpibooru because the comments on pages are generally respectful and often contain legitimately helpful criticism. If that stopped being true, I would ask that they please not be reposted because that’s not the kind of talk I like being associated with.