I'm sure drivers will cope fine.
Of course they will.
Give drivers 2 steering wheels to control at the same time with 5 pedals...they will cope fine. They won't go very fast and will probably have a higher chance of crashing...but they will cope.
The point is by giving drivers more things to do in the **** pit, it increases the chances of error (and possibly a crash). More errors also mean slower lap times.
The drivers who are best at multi-tasking are those that will fair best.