A troll-friendly wiki, especially a large public wiki is one that is extremely tolerant of rude or aggressive edit behaviour, including anonymous edits. In particular, it restricts and removes administrators for applying technological means of control to anyone who simply seems to be challenging the dominant authority or major voices on that wiki.
Another way this is stated is to say that those who accept administrator responsibility automatically accept Crocker's Rules as an aspect of that, and disavow ad hominem delete and other practices that violate equal power relationship norms. See troll-friendly and doctrine:troll for more general implications of this view, and tactics to enforce it.
The reason for the reference to the quasi-mythological creatures is clear to anyone who uses a net service for more than a short while. Calling someone a troll is a near-ubiquitous behaviour. Almost everyone will be called a troll in an attempt to intimidate/silence them.
Very shortly they will realize that the distinction between an administrator and a troll is, simply, who got there first to register the domain and set up the software - sometimes not even that. That is, administrators are "old trolls" and only that. Some so-called trolls assert that they are more capable of making key distinctions than the administrators, some not.
In the absence of any democratic means of letting the trolls run for the officer or administrator roles, being troll-friendly is at least a sop in the direction of democracy. In any wiki where democracy itself is the subject, the trolls represent the unwanted or ineloquent public, and must be tolerated on that basis as a sort of bellwether. The open politics in force rules emerged from just such wikis.
However, there are practical reasons to be troll-friendly too: Because the people who are not yet participating in the wiki are always, as a rule, more knowledgeable and experienced than those who are not, and because the odds of the administrator or founder being the very wisest person on the subject matter on this planet, a lively large public wiki depends on at least the possibility of ceding the key roles to a newcomer, one who brings the so-called new troll point of view, i.e. the emerging consensus among the dissidents who reject the administrative assumptions - or in parliamentary language, Her Majesty's Loyal Opposition.
It has also been observed that, from the perspective of the professional politician, the public are often seen as trolls, unwanted voices impeding their progress over a bridge that they perhaps should not be on. So political wikis must be somewhat troll-friendly.
The use real names and no anonymous edit policies are not troll-friendly: they discourage input from passers-by while encouraging a pathology that is called the wiki witchhunt. Those who accept the label trolls usually argue also that reputation is bad and that all ideas should be acknowledged and debated wholly on their own merits. These are the dreaded smug pro-trolling trolls. Beware! They are us.