Universities, for instance, would have real problems. Universities can often use other visa classes, but not always -- eg the J1 visa can't be renewed after five years.
The whole point of restricting immigration is to avoid the sort of race to the bottom that accompanies the corporate directive to get the best possible labor at the cheapest possible price. You only get that when you're able to cast a very wide net and allow in a population of people who can exploit geographic arbitrage to earn money in one area while planning to spend it in another. I'm specifically talking about people who have zero intention of ever relocating to the USA long-term.
It only makes sense to reserve the benefits of this country to those who invest in it. I'm specifically including corporations in that calculus. The goal of our immigration policy is to balance the needs of private industry against the interest of the state to compete on a global basis.