Ask HN: Breaking Countries into Smaller Ones?

I recently encountered the idea of breaking countries into smaller ones to alleviate polarisation, concentration of power, and military buildup.

I’ve heard of utopian scenarios where there’s lots of large communities that each live in line with their values. Perhaps it’s a similar line or thinking.

Anyway, to an uneducated mind this sounded interesting (not that any powerful nation would allow it).

Theoretically, if it were possible what would be the pros and cons? I’m guessing something like WW3 becomes less likely?