The Shard is the 47th largest building in the world. It's only notable in the absence of any other significant buildings in a nominally world-class city.
While I love supertall buildings, I don’t think height or size necessarily equates with notoriety, especially in a place like London.
Paris seems to do pretty OK on all of density, vibrancy, and aesthetics, while segregating all their somewhat-tall buildings to La Defense. I'm skeptical that moving all those into the city proper, let alone aiming for top-X-buildings slots, would improve the city in any way.
If the comment meant "tall" vs "significant," then granted. I think that, as a term of architectural art, "significant" means more than tall...