This will be a deal-breaker for over 95% of the applicants. Even though the H1B Visa is a non-immigrant visa, there was no such clause attached to it like this one.
It's what enables 1000s of immigrants (like me) every year to first arrive on a non-immigrant visa and then get the employer to petition their green cards for permanent stay or eventually citizenship. I personally know many immigrants who didn't really want to become citizens and intended to go back to their home country in 5 to 10 years timeframe, but applied for and obtained permanent residency (green card) just so that this uncertainty of resident status is eliminated.
Take that (the green card) away, why would any entrepreneur be incentivized to apply for this Visa? Because 2 or 3 * years is a very short time frame to create and run a successful startup. Why would any entrepreneur risk coming here on a temporary stay only to be banished just as the startup takes off?
* 3 = Number of years Kevin O'Leary (Shark Tank) says you give your startup to turn profitable before taking it to the back of the Barn and shooting it.