I guess Gary Bailey doesnt know what he is talking about then. Its not about starting, stopping or shifting, its about bike control. Check Gary Semics stuff too. Read this article, its a safety device, control device and traction control device. It doesnt matter what type of drive moves the bike at all.
http://www.racerxvt.com/article/gary-bailey-trackside---in-the-clutch
" then riders realized that the new four-stroke engine had lots of bottom end power and much better power, so they thought they didn’t need the clutch anymore. I never understood this because I always thought good riding was as much about controlling the power as having better power and you just cannot control your power without using the clutch."
"So lesson one: learn to use the clutch with just one finger and learn to ride with your finger on the clutch all the time so that it is there and ready if you need a little clutch to control your power.
It is important to understand how the clutch works to use it properly. You should think of the clutch as having a little traction control device. Think about how you use the clutch when you do a start. If you understand that how you release the clutch is important on a start, then you can understand can that how you apply and release the clutch is important everywhere else on the track too"
You can read the rest on your own. But to shorten it, The clutch is what helps separate the great riders from the good ones in the pro ranks.