Wouldn't this have the effect of changing the risk/return balance? For those joining your company early on, the risk would remain the same, but the return would fall sharply (by ~50%), while for those joining late in the game, the risk would remain the same, but the returns would increase a lot.
If everything else remains the same, people would be less willing to take risks and join early stage companies, instead trying to join near-IPO ones, where you can get a disproportional payout from minimum risk.
To maintain the same risk/return profile, you'd need to pay much higher fixed salaries to early employees and lower to late employees, which would probably drive the startup bankrupt on the early stage page.
If everything else remains the same, people would be less willing to take risks and join early stage companies, instead trying to join near-IPO ones, where you can get a disproportional payout from minimum risk.
To maintain the same risk/return profile, you'd need to pay much higher fixed salaries to early employees and lower to late employees, which would probably drive the startup bankrupt on the early stage page.