Any purpose to "unemployed" pops?

I did a search and couldn't find any posts about this. but I'm curious if "unemployed" pops actually do anything?

for example: I build a market village in a rural province, this allows some peasants to promote to 10 burghers and 50 soldier pops. well Burghers don't have any applicable buildings in rural locations, and soldiers are only useful if I build a castle or training field. Is there anything that these pops can actually "do"?

It seems like the only benefit is that is shifts the balance of estate power which might be useful if you're taxing certain estates more, but that's the only thing that came to my mind.