Well I understand your point, but clearly DirectX once meshes are cached can handle multi-millions polygons at comfortable framerates (personally I've been working on a 17 millions triangles car in max with 30 fps minimum constant, including textures display. MoI, even with very low tesselation (add details to inflections set to 5°) will run at 1-2 fps quickly with very daily models, which is a really annoying to work with in my humble opinion.
Since we (at feversoft) are working with realtime too, I can tell that meshed nurbs can display MUCH faster, so yes it is true :). We have a set of CAD importers that supports different type of nurbs and they all are showing great performance using caching.
My point about the on-demand caching is to avoid the lag during modeling (caching takes an instant to get done), also hide/unhide will destroy the cache but the lag is not SO annoying.

About the old gen graphic cards, well ok, but caching is supported even on the lowest grade dx9 compatible card I believe.