Yup you're going to get all kinds of opinions on all kinds of dolly's. The one each person uses will be the best and most capable--or at least "works for me".
They all work and will pull the car.
My guess would be that 3k weight is the axle weight you can put on the dolly (is that from the Acme specs?).
To add my $0.02: I've pulled 4 cars now with our Acme EZE-Tow dolly: Focus Electric, Escape, C-Max, and Chevy Bolt, and it "works for me"