Control spreads from your capital along owned locations and coastlines. Not having a connection to your capital in a location means limited control. This incentivizes nations to have well defined borders with minimal distance to their capital, though of course there will still be instances of border gore.
"low control areas" should be easier to lose, especially to a tag that is closer and would have better control of it.
edit: also, i bet not many would like such mechanic (and im not sure how it would work tbh), would it would be cool to somehow "lose" or "gain" territory naturally, without war, simply by having low control and neighbouring have overwhelmingly high control nearby. basically automatic "flip" of locations if certain threshold is met. maybe there could be a warning coming up, and the player (or ai) could combat it by placing armies there (short term) and build up whatever neeeded for increased control (longterm).
this type of mechanic would also create more natural borders, because you wouldnt hold territory if it is net loss, and more borders would be along geographical barriers, as well as cultural. and yes, some remote (barren areas might not have any tag controlling it, since it has no benefit to anyone (as i imagine it was irl)
edit2: i remember there were some similar mechanic in an old old civ-game, maybe civ3 or civ4... where if you dominate culturally your borders increase and slowly encroach on neighboring territory, and even engulf their cities.. loved that mechanic)
edit3: this mechanic could also trigger borders incidents, or give casus belli, or demand territory etc etc...