Hmmm, not really sure that's the case. It's basic engineering/physics, were talking a two-piece unsupported structure vs a solid structure.
Exert a force perpendicular to the lens body, over its centre. In the solid structure the stresses will be exerted over the lower surface, taken up by the material, which will not deform in the case of a metal lens body unless it leads to destructive failure, much like a load bearing beam spanning two points.
With a structure that consists of a weaker material formed as a tube within a tube, the stresses will all be placed on the area of the joint. The bottom edge of the inner tube will cut into the inner surface of the outer tube, and act like a lever. Of course we're talking about an extended lens, which you've steered away from discussing
This is not a point that can validly be argued from an engineering perspective. Without getting into force vector diagrams, ask yourself why bridges are constructed of solid beams and not loose tubes sliding inside each other. Or just extend the RF 70-200mm lens and sit on it!
Is it so hard to imagine that a company would trade strength and durability for weight and size in a product? It's done all the time with all manner of things.
The simple rule with engineering is that when you add to something, you take away from something else - because there is no such thing as a free lunch! The imaginary perfect material or structure that is the best at everything and fits every need is nonexistent by definition.
Probably best to be aware of the potential weaknesses of a new design and treat the gear with respect to ensure it doesn't get damaged, rather than assume it's better in every way because it's newer, that would be a logical fallacy.
Practical advice, don't treat an extended telescoping lens made of engineering plastics as it it were a solid, single-piece alloy traditional big white, that would be a sure way to wreck a really good expensive lens.