It wouldn't be one persons fault, but as we all know, accidents rarely have a single cause. Rather they are a combination of factors.
In the case of Weston, if I had heard that someone had flown through the middle of a glider launch and had walloped into someone else, then I would be thinking "what an idiot, putting themselves and others at danger." BUT if I later heard that this was a problem that had been happening on a regular basis, but this was the first accident that had happened, then it would seem sensible to start questioning other factors ontop of the stupidity of one individual.
As someone far smarter than I said once "safety is no accident" and we ALL have a responsibility to try and minimise any potential problems.
So in a way, if an accident does occur because of an issue you've highlighted, but done nothing about, then yes you do have to take some responsibility.
One last thing, the vast majority of airborne GPS recievers don't just take you along a line with no thought to what's around. All that I've used (pretty much all of the available makes) tell you what airspace and whether there are restricted areas or danger areas around you, so in theory, if you are following the GPS only and not looking out of the window, it should show you and usually tell you when you are close to somewhere like D129, so I don't think your problem lies with over reliance on GPS, rather the opposite in fact.
If you use a something like a colour moving map display, then you would be amazed by the amount of information available to you, including the location of danger areas.
One point about whinging. if you are grumping on about someone's actions, but not prepared to do anything about it, then you are whinging. If however you intend to try and resolve the situation somehow, then you are passing on information and not being a whinge bag!