But the opposite is true, too: They can't, because their vehicle is not capable of it. You don't need to be doing 60 MPH in 3 seconds, but being able to it in 5-6 is much better (for everyone) when merging onto highways.
Also, you know, there are a lot of vehicles that are much slower than 10 seconds 0-60 on the roads, even though 10 seconds has become pretty much the maximum for late model cars in the US. Commercial vehicles aren't going to disappear or do 0-60 in 5 seconds even if they had the power.