I've been reading on the GD forum since 2014 when the 303 was the big new 5th wheel. Yes you get negative posts on owner forums. You also have to decipher those posts as well. Complaining about a vendor supplied part is different than complaining about a leak, bubbled roof, squeaky floor, paint rubbing off the kitchen island, under rated leaf springs etc.
I read the Forest River, Jayco, Keystone, Irv2, Northwood forums. You can pick and choose problems all you want. But spend time on the forums and you get a feel for what problems are MFG related and what are vendor related.
With that said I'd buy certain model GD trailers. Some I wouldn't. Where GD excels is in customer service and IMO unique floor plans.
GD knew they couldn't make a better trailer so to gain some kind of advantage and to try and set themselves apart from the rest, they went the CS route. It worked too. As you'll read many times thats one of the things buyers like. Everyone knows that most all RV's have problems. Knowing that you may get treated better than the rest is comforting to some.
I think it's called 'Marketing'.