Basically, Taboo is a program that aims to make drum tab editing as painless a process as possible, by providing intuitive controls to let you work with tablature in its natural ASCII form.
If you've ever tried writing a drum tab from scratch, then you probably know it's pretty hard going. You fire up Microsoft Word or an equivalent, type out some |'s and a whole lot of -'s, then copy them around until you have a few lines made up of a few bars. Then you can fire up your music, and start selecting some of those -'s and punching at your keyboard to replace them with letters.
Perhaps you get lucky and this song you're tabbing sounds a lot like another song you already have a tab of. So you open that up in Word and grab the similar verses and start editing away at them. You quickly realise however you're better off just copying your newly-edited bar for the rest of the song than using anything already in your old tab. And so it's back to the play-pause-point-select-overwrite-rewind-play loop for the next few hours or so.