I have an Otterbox myself and just my opinion - that technicien's comments don't make any sense to me.

Humidity is in the air everywhere and in North America at least - the places where you'll find the lowest levels of humidity are indoors. That's just a side effect of creating a heated, sealed environment. It's impossible to totally prevent issues with condensation - and cameras are no different than cellulars. And I can't think of a more appropriate way to minimize condensation issues than by sealing a package indoors.

I'm more of the opinion myself that the problem was caused more by regularly subjecting the cellular to conditions that promoted condensation ( extreme cold / extreme humidity ) rather than by the level of protection.

None of the ports are actually sealed against moisture with or without an Otterbox, and I personally appreciate the shock resistance of the additional case.

Something to think about: If you were keeping the iPhone in an inside pocket - that's a high humidity environment because of perspiration and that's probably all the Ziplock is effectively protecting it from. A ziplock would be a good idea there with or without an Otterbox.

And reception issues due to interference from a small amount of plastic and metal? It takes a lot of steel and concrete to do that. A bit of plastic and silicone really are no promlem for reception. The iPhone case already uses it.