I have a ranger: why not give a third attack at some level (higher than 11)?

I have a ranger ?: why not give a third attack at some level (higher than 11)? that would add DPR without discounting fighter, who gets that 4 APR at 20th. I see hitting 3 or 4 attacks to be a fighter thing, would rather boost damage elsewhere for the class

— Mike Mearls (@mikemearls) September 5, 2018