IDK, my team at a FANG has an average tenure of around 7 years and the ones less than that are new hires. I keep getting refresher grants every year. I'm sure this article rings true for some people but not me.
The job hopping thing was definitely a trend, but I think it died with ZIRP. kinda weird to reference it now, but I guess it does have relevance to the state of some of these older services. The original teams are long gone
github does not have a good engineering culture compared to FAANG, they've had some horrible outages and made some questionable scaling choices.
I'm an "old-hand" at a non-FAANG big tech, and have not had a meaningful refresher in a few years, or even a salary bump for that matter. This is a bad time to be looking for a new job, but I should have jumped ship years or even decades ago. I'm sure I'm under-compensated for my level of experience. Don't get caught in this trap like I did.