why do some dislike clutches?

when i was using a 7xl no clutch but direct drive and found this to be to fast against the nitro's i found by going to mech brakes and switching of the speedo brake this also increased my run time but at this early stage of testing i was only using 2200mh 4 cell lipo and was unable to get the 5 mins i would only get 23 laps but the mech brakes increased it to 31