What can save your ass is automatic formal verification and static analysis. That's hardly what I'd rate as "primitive". That a lot of people carelessly throw

What can save your ass is automatic formal verification and static analysis. That's hardly what I'd rate as "primitive". That a lot of people carelessly throw together CRUD apps does not contradict what I'm saying. In fact, I'd say most CRUD app development is highly primitive, notwithstanding the complexity of the web platform itself. Debuggers do tend to sometimes to mask heisenbugs, but this goes the same for just about any tool performing intricate binary analysis. And there's some subtle timing bugs where it's a fact of life that you'll get misleading readings.