We actually experimented with different ways of fixing this. For example, that you can only use operations in a zone that you have a hero in, or a special "spotter" unit such as a modded scout. Another idea was to allow war ships to project "operation coverage" to adjacent sectors, so that you could use them a little bit like a modern boat would fire off cruise missiles.
The main issue we ran into was that it was extremely hard to communicate how had coverage where. The player already needs to keep track of who owns a sector, but then they also needed to see who had coverage, and a single sector could have coverage from several players. We had no way of visualization it that wasn't really confusing, so we decided to see what would happen if we just used vision range like we have now. Although it does indeed feel a bit odd, it didn't actually give any real balance issues during testing, so we kept it. If for no other reason that it worked, and it was simple, and the game is already complex enough!
The main issue we ran into was that it was extremely hard to communicate how had coverage where. The player already needs to keep track of who owns a sector, but then they also needed to see who had coverage, and a single sector could have coverage from several players. We had no way of visualization it that wasn't really confusing, so we decided to see what would happen if we just used vision range like we have now. Although it does indeed feel a bit odd, it didn't actually give any real balance issues during testing, so we kept it. If for no other reason that it worked, and it was simple, and the game is already complex enough!