Why the Joffre class was not a design dead end

Why is it inaccurate to call the Joffre class a design dead end?

It was a generally sound next-generation French carrier with room to evolve, despite weaknesses in its landing arrangements.

The Joffre class offered a sound base from which later French carriers could have evolved. It represented a genuine next generation rather than an evolutionary cul-de-sac. The landing arrangement was the clearest feature that invited revision. That weakness does not make the overall design poor or incapable of further development.