I generally play loose and fast PLO, so a gutshot with an overpair is close to nuts for me.

I do understand the point about being semi-passive, as I actually play a style that varies between loose-agressive/passive and pure tight-aggressive in the cap games, depending on the table make up.
The reason really is the fact that a lot of people at microlimits will call you with just about anything in the flop if you instantly toss out a continuation bet, which means that if they hit something, you might have hard time taking the pot away from them. If I notice that people are calling me loosely on the flop, I wait until I actually have a hand (or half of it). I also check a lot in multiwaypots and OOP with chronic checkraisers, before making a play at the turn when I'm more confident that no one has anything, or I actually hit a hand.
The beauty of CAP PL games from this point of view is that you can't really afford to chase as much, and some players don't realize it. And those who do will just give the pot away, so the question just becomes who knows how to fold, and who doesn't. $17 pot with a $40 cap doesn't leave too many implied odds for straight or flush draws on the river.