That "limitation" appears to be the pressure at which the outflow valves operate and not the operational limit. According to the [link](http://www.b737.org.uk/pressurisation.htm) you shared:

> At cruise altitudes above FL370, the **max differential is 8.35 PSI**. which will result in a cabin altitude of 8000’ at FL410.

That second quote which states that "outflow valve on NG and max operate at 8.95 PSI" is incorrect. According to the [Boeing 737 FCOM](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.pilot18.com/wp-content/uploads/2017/01/B-737-7-8-900_FCOM_TBC_C_080125_V1V2_B8P-C.pdf&ved=2ahUKEwixqfj627z9AhX2-TgGHQzpBiIQFnoECBEQAQ&usg=AOvVaw3SUorKAnjtOuJk8pViXSpV) (page 751):
> Two pressure relief valves provide safety pressure relief by limiting the differential pressure to a maximum of 9.1 psi.