Why is it that pros keep their playing partners score during a tournament round, as opposed to their own score?

I read that Sergio Garcia was disqualified after signing an incorrect score card that his partner (Boo Weekly) recorded during their tournament round.

Is this just an old-dated tradition that has survived to modern times? It just seems so inefficient that a pro has to keep track of his partners score, as well as his own in case his partner made a mistake.

Pro or no pro, people arent always 100% honest there would be alot of false scores running around. Its pretty easy to keep your competitors score.

Cant put all the blame on Sergio. It is the player's responsibility to double check the entering scorecard to make sure it is correct, before signing.

If its wrong before signing then you can fix it. If you sign for a score that is lower than what you had.. you are DQed. You are fine if you sign a card that is has a score higher than what you actually had.

I never really understood this either. So, for example... my playing partner knocks his tee shot OB, shanks a couple down the fairway, accidentaly double hits his ball, finds the water on the approach, chips on, and five putts. I have to calculate all those strokes? Don't the pros just write down what their partner said they scored on the hole anyway? "Hey Serg, I got a 5 on that one, ok..." I'm too engrossed in my own game to bother adding up someone elses strokes.

yeah, it's not like their is scoreboards on every hole or anything.

When people make a big number, you sometimes have to rely on them to be honest about it. I'll only have to ask about once every 2 or 3 tournament rounds. Usually I know, even without consciously "counting".

It's been this way like forever. Unless you play a casual round you always have to have someone else write down your score.
That's why the pros when they have to play alone in a tournament have a marker beside them to take their scores (sometimes playing or mostly non-playing).

Usually in all rounds counting toward your handicap there should be someone else writing your scores, can't be everybody as honest as the members here, right.
I have yet to play a handicapped round without a marker. Usually at our weekly medal games we play in threesomes, and although you're only required to keep your player's score most of the time you write down all three scores, just in case a dispute arises, but of course ultimately you are only responsible for your own score in the end.

There is a nice story about two pros in the Open Championship a few years back who mistakenly forgot to exchange scorecards before the round and were disqualified for that.