Stalker 2.3 diode

I have purchased some Stalker 2.2 boards and from the wiki I see that there was a diode added between LI_BAT and USB5V on the v2.3 board. The schematic shows that it allows the battery to supply the USB5V line with voltage (3v3) when USB power not present.

Without the diode, what are the consequences of not having that connection :question:
If I do not add the diode what problems might occur :question: