One perspective is that the exchange permanently hamstrings the company. You spent let's say 3 years on average, training those engineers to be the best people in the world at solving Stripe's problems, but now they're gone with (unless you're gonna do double payroll for a while) only an arms-length handoff to the new staff. That's 300 person-years of training, gone forever. Arguably even worse, it propagates upwards; there will be some number of valuable, important projects which can no longer get done because the needed expertise was lost.