It's only been perennial leapfrogging for the past several years, when AMD has been doing well with their Zen processors and Intel has been on a recovery path from their 10nm failures. But before that, there were a few stretches of several years each where Intel was solidly in the lead and AMD was always an also-ran. Intel couldn't have retained their dominant market share for decades without having those long periods of undisputed technical leadership to solidify their lead.
Sounds like someone either wasn't around for, or forgot about, both the Athlon era (when folks were just as likely to have an Intel as they were AMD), as well as the 486 days, where folks were just as likely to have an Intel as they were a Cyrix (thanks, Quake, for ruining that party).
It's not "only the past few years", it's "we're back to healthy competition" after a period of basically illegal business practices breaking the market.
But people are pining for the "good old days" where Intel sucked, but AMD sucked more. Now these two companies are competitive and innovating. This is how it's supposed to be.
