The idea is to keep everyone making the market rate without them having to job hop every few years
Generally software engineers get crappy 2% raises year-over-year and may or may not get significant RSUs/bonuses, while the market rate is flying up 5+% per year. I think most people on this site who've been working for 10+ years can attest that they snagged a 50% or more pay increase by changing jobs at some point.
I'd still be working at my first crappy post-college job if they'd been nicer to me and I were within 75% of what I can make at a nearby FAANG. But I snagged a 100% pay bump (DOUBLED pay) by changing jobs. And then I doubled my pay again a few years later! And now I've been in my current job 3 years, and I'm pretty sure I could get a 20% increase by changing jobs again even with the recession.