<Snipped quote by Little Bird>
You realize without bodies, making a check to wealth means nothing? For example, if I have $100,000 to build a house but I do not want to hire a group of people to build that house. How is that house going to be built? How is that money going to actually be used? Having personnel a little distracted from wealth investments just makes sense. You need someone/some people at least to focus on whatever you are upgrading.
You cannot upgrade an area and just think it'll magically be upgraded without anyone touching/working to get it upgraded.
Now, I could see there being already established weapons/gyfts/etc... in a personnel and your character sending out troops to go fight another district/take other a district without expelling extra money.
But to spend money, especially on something like upgrading/building. You need to actually have people to do that.
From a realism standpoint, you're correct. Bodies are needed the build/repair things.
From a game design perspective though, we're running two stats that are functionally the same thing; Personnel is an extension of Wealth. It serves no distinct mechanical purpose as of right now.
In the vein of realism we can just as easily say that the factions themselves aren't putting their manpower into the upgrades; rather they're investing monetary resources into the community and outside entities are using that momey to build and develop.