My personal opinion, and it is only an opinion, is that some of the older hulls are far stronger than the hulls built today. Some aren't. The glass fibres in a hull will weaken if they are subjected to repeated crimping or other compressive forces, as they are crystalline structures and once they're deformed, they don't resume their original shape.
The resins that were used in the very early days of FG boat building were not the ultra-sophisticated sompounds used today, but the yards used lots of resin and lots of glass.
This resulted in strong, stiff hulls. It is the stiffness that contributes greatly to the longevity. Because the boats flex less than many of the more recent, lightly built models, the glass fibres deteriorate less quickly.
The early resins were not very UV resistant. Hulls that have not been protected from UV degrade more quickly than those that have been sheltered. The osmotic blistering issue is something that varies from brand to brand. Again, the thickness of the layup is a factor. A thinner hull doesn't have a lot of excess resin to sacrifice. It takes less time for water
to work its way into the core
and less time to weaken the boat seriously.
Finally, the sheer mass of the thicker hull makes it better able to withstand trauma resulting from collisions, groundings, or other mishaps.
There are millions out the who will disagree, but - heck - there are still a lot of smokers out there too.
Good Luck ! Hope things work out well