SEALs aren't the only ones who carry pencils and paper. Most troops do, if they have a lick of sense.

Pencils don't run out of ink. You sharpen them with a knife as needed. Eraser runs out, no problem, sharpen that end too.

Paper. Personally, I carry 3x5 cards, as well as 5x8.
Range cards for fixed postions
Sketches of recon objectives
Writing out orders in standard 5 paragraph format
many more uses

Didn't carry a wallet in the field. Carried my notebook with the 3x5 and 5x8 cards in a plastic bag. In smaller bag in notebook was id card, military license, some cash and change. I lost a wallet in Florida one time, was a pain to replace all the stuff, so I carried minimal to weeds after that.