I had a Holiday Rambler 34CBFK, supposedly (said tongue in cheek) one of the best. No delamination because it was all aluminum skinned. HOWEVER.... It was riveted together in a "temperature controlled" assembly line so the metal skin was at "medium temperature" and sized to fit the trailer. UNFORTUNATELY, when it sat in the sun (most of the time in Louisiana) and the skin expanded in the heat, it looked like an accordian. Talk about "oil canning" That trailer had a pretty bad case of it. I was asked more than once what ran into my trailer to squish it up like that.....
Something to be said for fiberglass. It also has it's characteristics, but so do all other types of RV materials.
I suppose there's good and bad about all of them. But to complain because an "older Cougar fifth wheel" is delaminating? The trailer that is being criticized may well be 20 years old..... I'd be happy if it were mine and lasted that long
So, to put things into perspective, just how old is this Cougar?
Keystone uses fiberglass (filon) side skin purchased from an outside supplier, the same supplier who sells to a large number of other manufacturers, so if you buy from "another brand" you're still getting "keystone skin" The same is true with Lippert frames and Dexter axles.
Outside suppliers sell to most RV manufacturers and the materials used to build RVs is pretty much standard across the manufacturing line. Seldom is anything "unique" about an RV other than color, floorplan and design. The same skin, framework material, flooring, carpet/vinyl, cushions, appliances, windows, insulation and running gear go into most models produced by the vast majority of manufacturers.
No RV is without it's potential problems, not even the best..... Airstream has had its share of broken frames, buckled skin, leaks, rust, rot and malfunctioning appliances just like Keystone.