It doesn't absolve teachers from the need to maintain discipline
Very true - however there are some pupils who really don't have anything to lose.
Throw a chair - what sanctions are available? Not allowed to send them out, not allowed to send to Head of Year - only to head of department who also has a class of the same year group with all the pupil's cronies in. Two classes disrupted - because someone threw a chair.
Give a detention - such pupils are generally booked up weeks in advance (24 hours notice must be given) and don't turn up anyway. If they don't turn up, what do you do? Procedure is to ring parents and re-set. Then you have a 15 min conversation with a parent who blames you for their child's poor behaviour "you should maintain discipline - but no he can't do detention because he has a paper round. etc etc"
By this time several days have passed and you have had to teach said pupils a few more times - maybe he has thrown more chairs in this time and there are several detentions in the offing, which he won't attend.
Probably you have more than one such pupil (look at the amount of teacher time/work they generate, this is before any prep/marking/admin is done)?
Eventually, if you are lucky, the matter is escalated and the pupil MAY (only may) get a short-term exclusion (if your school does exclusions that is). A few days on the Xbox and then back to more chair throwing. Happy Days!