I feel like I'm in my internet dotage. When I started out online, reading blogs, commenting on blogs and blogging myself, centuries of internet-time ago, I had a sense of what a troll was, and why s/he was a bad thing. Now, increasingly I see all manner of dissenting comments, comments framed perhaps vehemently or carelessly or sometimes even fairly courteously, flagged as trolling, and the commentators warned that if they repeat their comments they'll be banned. A recent example: this Chris Betram Crooked Timber post about the legacy of colonialism: 'Skeletons in the Imperial Attic'. I broadly agree with Bertram in this post, and disagree with the first comment, from 'Jawbone' ('this is pure white self-hatred'). But it seems to me that 'Jawbone' has a right both to dissent from Bertram's view and to articulate that dissent, and that he doesn't do so here in a way liable to incite hatred or cause a breach of the peace. A couple of other commentators expressed their disagreement with 'Jawbone', which is all good. Then Bertram commented: 'Had just decided to zap the troll, but now there are referring comments. Jawbone: further comments from you will be deleted. Other people, please ignore.' Not so much 'I disagree with what you say but will defend to the death your right to say it' as 'I disagree with what you say but will defend to the death my right to block, unfollow and no-platform you.'
Calling someone a troll implies a judgement about their intent: it is saying not just that they are disagreeing with you, but that they are doing so in bad faith, just to get a rise out of you, disingenuously, wickedly. But increasingly, it seems to me, 'troll' is becoming a synonym for dissenters of any stripe. That's not a good thing. In the light of this, it's a particularly bad thing.
Of course, 'Jawbone' can always get his/her own blog and say what they like; and of course the comments thread of somebody else's blog is space that belongs to that other person. But it's a public space, for all that; courtesy is an ideal rather than a necessary condition of debate, disagreement is healthy and 'troll' ought to be a rhetorical blade unsheathed only at last resort.