It is still debated on Internet forums such as Wikipedia from which most of this is drawn "whether or not trolls, (participants who generally refuse to be bound by a code of conduct) perform any useful function."
Because troll is such a broadly-applied term, if all definitions thereof are to be accepted, the answer is unlikely to be definitively, "yes" or "no".
[+] trolling is mainly a waste of time.
[+] Pro-troll view
The right of anonymous trolls in particular has been upheld by literally all credible people who study Internet culture at close quarters. The Infrastructure of Democracy, a 2005 manifesto by some famous bloggers, emphasized anonymous trolling as a right of citizenship as such.
Advocates of trolling refer to the Federalist Papers, the requirement of the Knights Templar to anonymously assist any persons who they might meet "to gain their rights" regardless of offense to authority, and other examples that they claim are equivalent to "being a troll".
The collaborative writing on the US Constitution by known trolls who happened to be Founding Fathers of the United States, is an extreme example of this avowed usefulness:
- Whatever of the power and persistence and prosperity of the United States which is attributed to its structure can reasonably said to be trollwork
- The collective reputation of Publius was such that it justified the trolls taking extremely central roles in the early government and shaped its structure to the present day.
Such observations are quickly removed via sysop vandalism from Wikipedia, however, where there is a small clique called the Young Jacobins whose persistence at removing blankly pro-troll statements has been cited as one of the key demonstrations of power struggle in troll culture. Other players in this are TINC and the Wikipedia red faction.
[+] oh the humanity
Much of the confusion stems from the fact that all "users performing many useful, but controversial, functions are often decried as trolls, and in these cases, so-called trolling may actually benefit the forum in which it occurs. For example, the presence of a radical right-winger described as a troll may allow a conservative lurker to feel more comfortable expressing her viewpoints, which seem very moderate in contrast.
On the other hand, if trollhunters mount a flame war against this right-wing troll, the conservative bystander may feel less comfortable expressing her views, to the detriment of the forum. As much as trolls claim to fight groupthink, they may actually encourage it by solidifying opinion against them." Though perhaps the better to unify and smash it all at once, this being a principle of Sun Tzus:
:when the enemy is weak, attack their strength
[+] new clothes reviewers?
"Trolls may also provide a valuable service by making people question the validity of what is read both on the internet and from other sources. Trolls show that expressing any opinion is as easy as expressing an informed and considered opinion and may get as much visibility. It is arguable that shock jocks, some newspaper "hack" columnists are trolling public opinion." See the list of known trolls which includes such people. Of course, Publius was in its time also "trolling" those who "knew" that there was no alternative to constitutional monarchy and that there could never be a judicial branch that was wholly independent of the rest of the government.
"Even though useful content and productive users are sometimes decried as trolls, the general consensus is that pure "trolling" benefits only the troll and trollhunters, and has no place in any forum.
Most forums reject the claim that pure and intentional trolling serves any useful purpose." This confuses a troll with a troller however: one who adopts outward troll characteristics in order to just have fun.
[+] trolling is fun
A final useful factor is the Play Ethic:
"Trolls can also in some circumstances be a source of genuine humour, which depends entirely upon whether the troll is a good or a bad troll. It's usually fairly easy to spot the difference between such actions, bad trolls resort only to weak uncreative arguments, or nasty rhetoric whereas a good troll will create a subtle set of arguments which draw people in with cunning twists perhaps even supply a little humour" or point out some paradox, especially an ethical paradox.