The dot-com bubble? Which ballooned in the late 90s, then burst, with investment not returning to 1999 levels for about a decade (also thanks to the 2008 financial crisis).
Their point is that we've been stuck in 1999 for 15 years, and not the decade before that.
Disagree all you want, but “it's been 25 years since 1999, you fail at math” makes no sense as a rebuttal.
