I started having problems with vacuum lines blowing off the fittings right after I bought the car. I had many instances where it'd be running odd, I'd pop the hood, and the line to the fuel pressure regulator had separated itself from the nipple. Several times the entire bunch had decided to separate themselves from the junction block on top of the throttle body. I ran for years with a massive zip tie holding that mess in place. I'm pretty sure I'm not alone. Maybe if you're only running 14psi it'll be fine, but if you turn it up, some kind of positive retention mechanism has to be on any line attached to manifold pressure.
I'll happily pit my engine by environment against anybody's in terms of harshness. I've melted everything. But I haven't had a line come off a connection.
Push-loc aside, if you aren't clamping anything attached to the manifold, you're asking for a hose to pop off a nipple and a bad day.