Comment by Jach

Good point, it was sloppy of me to call them same-generation, I distracted myself with thinking about Kasparov's long reign at the very top which I view as defining a sort of competitive era ("generation") that was shared for the majority of Karpov's active career at the top levels as well, even though it extends past that and Karpov had his own period prior to the Kasparov rivalry. It's interesting to bring that back to the question of how much age matters though since Karpov kept playing and was also still very strong against the even newer players (Anand and Kramnik being 18 and 24 years younger) for most of the 90s too.