That sort of implies that going above f/2 is a lot of money for not a lot of benefit. Hrm.
Yes, you get less than you expect.
This is the reason why I love my old EOS 5D, with microlenses that only loose 0.4 Exposure Values with a f/1.2 lens, and not 0.95 EV like the EOS 7D.
On the other side a f/1.2 lens is still faster and still with more blur than a f/1.4 lens on the same camera.
But probably a f/1.2 has less blur on a DSLR than on a old film camera.