WHY does the battery on the motherboard matter?

Here is the deal. A computer at my workplace would not boot up after shutting down. It would boot up if I waited at least ten minutes or more. My supervisor said to change the battery and the problem was gone. When I asked him why, he said he didn't know and the only reason why he suggested it was because he fixed another computer with the same problem. Do any of you know why? Thank you for your time.

I thought that the battery only supplies power to the CMOS chips and keeps track of time. The BIOS is supplied by another source for its power.

The only thing the battery does it to power the real time clock/cmos memory, so the content won't be lost when you cut the main power.