Development experience is not necessary as a PWA, its just considered additional useful experience. If they are able to spot a problem and are able to fix it, such as with gmaps, it just saves finding someone with that ability. Most of those things you just learn though while you are a PWA.
At times I find it to be a disadvantage to actually understand it. Such as during inspections. We should be going on a server to look around just as a brand new shiny newb that has no clue as to how Graal works. We play the server, see how it feels and make our judgements from there. Its up to the GST to tear them into little pieces and see if they actually know what they're doing or not.