AS a DM, my focus is on the everything except the players' stats - I let them keep track of their one character as I do all the environment and NPCs. I even ask one of the players to keep track of initiative order as I find trying to remember attack features for multiple monsters suffers if I am multi-tasking too many other things.
How many of of you DMs keep track of all your players' stats?
And if so, why?
I keep track of bonds, traits and flaws so that I can try to drop those in when I can (less than I really wish I did).