I think that would be the case regardless of whether a balance rule is included or not, however, with such a rule, there would be no gameplay difference if neither side ever had more than 5 things that could patrol. I wouldn’t say that only swarm specs end up in situations where you have more than 5 things that want to patrol, however.
Not having a balance rule would allow for interesting strategies like putting all your Illusions in the Lookout slot, which I don’t think is necessarily bad, but it does go beyond trying to allow more than 5 things to patrol at a time. I’d be interested to try it without a balance rule, but I feeling like it would be more likely to have wacky results.
My hope and motivation for this idea is that games would tend to last longer on average… more specifically, that in games where both sides are gradually building up forces, it would be more difficult for one side to suddenly break through the patrol zone and take down key buildings, which would in turn perhaps lead to seldom used backline cards becoming more relevant.