Big reason why I try to find a buddy is a safety issue. I like to cover ground and try new spots and that involves lots of wading and hiking around. By myself no one would know where I was if anything were to happen to me (fall in, break a bone, etc.) and phones don't usually work where I fish.
My dad's friend snuck off one lunch break to fish a little by himself and fell off the trail and fractured his leg in three places...thankfully his cell worked otherwise he probably would have died since no one knew where he was.
I always leave a note with the river I'm fishing and an estimated time of return (only had the family call the cops once when I didn't return...fishing was just too good so we stayed late) but so many times plans change. Good to have someone else with you out on the water.