That is technically correct, but "b" has never been an accepted abbreviation for baud (which was Bd) and the naming of the first versions of the PCIe, USB 3 and SATA speeds, which were done by Intel, were obviously in contradiction with the industry standards and intended to confuse the customers.

Previously to these standards promoted by Intel, the 1 Gb/s Ethernet used the same encoding and it was rightly called by everybody "1 Gb/s", not "1.25 Gb/s", because the gross bit rate has absolutely no importance for the users of a communication standard.

Only Intel invented this marketing trick, calling PCIe 1.0 and 2.0 as 2.5 and 5 Gb/s, instead of 2 and 4 Gb/s, and similarly for USB and SATA, where e.g. SATA 3 is called 6 Gb/s, but its speed is 4.8 Gb/s.

To be fair, what Intel did was not unusual, because in the computing industry there has been a long tradition of using fake numbers in marketing for various things, like scanner or video camera resolution ("digital" zoom, "interpolated" resolution), magnetic tape capacity ("compressed" capacity), and many others.