Don't we need to warm up before doing any max intensity exercise to prevent injury.
I had assumed this was about sprinting in the sense of running as fast as possible, which would be absolutely insane to do without a warmup. I take around 20 minutes to warm up for sprinting, doing very specific exercises to prepare.
On a stationary bike though, because the range of motion is much more controlled, I can see it being a little less of an issue.
But I agree that going full force very briefly on a stationary bike with no warmup is probably fine for most people.
I'd expect people doing these regular sprints to be more aware of their body and move around more in anticipation of the next set.