As a practical measure it’s really not. The transition is difficult for existing companies, but a future startup is going to be minimally impacted.

Year 0 you’re unlikely to have any profits, future years you have multiple years of R&D to offset with.

But let’s assume the worst case. Taxes are 21% of profits and at minimum deduction 20% of R&D so the theoretical maximum distribution is 0.8 * 0.21 = 16.8% increase in R&D expenses if profits = R&D year 0. But that maximum case is only year 0, you’d be able to fund R&D with those same profits and easily be profitable after that.

If profits where say 40% of R&D in year 0 you’d have to pay 16.8% of 40% so an increase is only 6.72% hardly likely to tank the business if it’s already generating that kind of income year 0, and again after that point you’ll deduct for multiple years.

More realistic numbers are going to be really low multiples here, more importantly they represent significant investments not operating expenses.