That's a step further than necessary. What's needed is for 50Mbps to mean by default that it's a 50Mbps best-effort connection without any artificial throttling below 50Mbps. Congestion is unavoidable and even a "dedicated" line will at some point put your packets onto an oversubscribed link if it's a real Internet connection and not just a point-to-point link. But it's inexcusable to sell something as 50Mbps when it's really "50Mbps for part of the month, then you're screwed".

There's a world of difference between "speed will sometimes drop due to congestion" and "speed will definitely drop by throttling", and a dedicated line is way out of this spectrum :-).