Leaving macbook plugged in and on 100% all the time
The Macworld article reflects best practice.  The battery is designed to be used.
I wouldn't be too concerned about dropping the charge to 30% every day.  Even dropping to 80% will help.  For a long healthy life the battery should be used.
Of course, if you keep it plugged in all the time you don't have to be worried about keeping the battery healthy!
Just to say it again: The battery is designed to be used.