(hey! neutrois-anon from the gender thread here again.)
Like you, I have a different history with self-harm: in my school days, which were pretty excruciating, I would often (weekly or more at the worst of it) get upset or panicked to the point of compulsively hitting or slamming my head against desks or the wall. It wasn't really a coping mechanism (except insofar as it was the only reaction I had available), and although I am no longer in anywhere near such a caustic environment at the moment, I do have minor ticks (most recently, biting, but not to the point of breaking skin). But I've never cut, and I believe my actions are not the same phenomena nor on the same level of (for lack of a better word) severity as cutting, so while I have followed these discussions, I have not considered it a place where my voice was warranted.
I'm wary of your application of prescriptivism to the FWD thread. What I saw on that page were personal accounts; whether a behavior is unhealthy for the speaker is completely different from shaming others away from using that behavior. For instance, use of medication for a given condition might be unhealthy for one person and not for the next, with both experiences being valid. It's only prescriptive when you make the personal universal and state that no one ought to utilize a behavior simply because it isn't right for the speaker.
I would not assume that the OP's self-harm was working for hir simply out of lack of explicit language to the contrary-it's clear that ze considered it a poor enough solution. And as to criticizing the OP's recovery and coping methods, that strikes me as truly prescriptive regardless of whether hir own post was such.
This is the wrong approach to take on the issue. Rather than making the discussion about what is good for a specific speaker (as ze is clear enough on that), it should be about what perspectives are not explored, whose voices are not present, and why. Coming from the perspective that self harm is not a universal negative for everyone utilizing it, the problems to pose/address are: Is this discussion leaving the door open to those with a variant relationship with self harm and if not, why not? Are those voices even present to be included, and if not, why not--is it because these people are very rare, or is it because the local (site/movement) environment is hostile, or is it because they have been ostracized and silenced in society at large, etc.?
As to the sm feminists post... I was recently reading through that comment string as well. My thoughts are less straightforward. But I disagree with much of the points dh made.
Trinity (basically) makes the point that self harm is not intrinsically maladaptive, but that it is disingenuous and unhelpful to conflate those for which it is and those for which it is not. They have different needs, needs which warrant respect, which means that psychiatry should be an option but not a universal response. She acknowledges that psychiatric intervention is not the best response to those like dh, but says that this is not true for the "vast majority" (not personally prepared to evaluate the veracity of that claim, but would not disagree).
She and Bean both make the point that induced pain in the context of harming and BDSM are utterly discrete. On this, I am not completely certain-at least one person on the FWD thread, for example, mentioned BDSM use as an alternative coping mechanism.
At the same time, I don't think dh's use of BDSM should be endorsed by the BDSM community at large. As per this quote:
But overwhelming, irresistible desire? Yes, I have experienced that for both scenarios, self-injury and BDSM acts... not in the sense of 'really wanting a good sexy spanking' but rather, frantically begging my partner to do something to me before I did something much worse to myself, yes.
That sounds to my ear like coercive behavior. "Do this to me before I do much worse to myself"... That's manipulative. It's a threat.
And while I would not be in the "inarguably discrete" camp, I see hir insistence to put BDSM under the self injury label to be erroneous, serving no apparent purpose, need, or logic. Intersections do not make the concepts equivalent by any means. Being involved in BDSM does not imply that one has self harm proclivities or vice versa. Bean's scary movie/true danger comparison is a powerful one on this point.
But Bean makes this point here...
And trying to convince anyone that it's totally okay for some people to feel the overwhelming desire to do something dangerous to themselves is wrong.
... And that's just not true, in my opinion. People do (what can be) dangerous things to themselves and it is not something fundamentally wrong. Driving a car, smoking/getting drunk/(insert risky or addictive behavior which is tolerated so long as its effects are restricted to the individual), meeting people. Living.
This statement is prescriptive-it defines a behavior as universally dangerous for the participants and makes the call on responding to the behavior for them rather than allowing for their own agency.
And about that. Prescriptivism. This is a powerful line of argument that consolidates so much problematic trash in feminism and other discourse into a single, coherent idea. But there is a point when something stops being prescriptive in the pejorative sense and starts actually needing to be prescribed (so long as it retains the agency of the other party) - e.g. describing much of healthcare. The logical boundaries here are complex, but nevertheless important to respect lest the worth of the argument be damaged.
Finally, RE:"Trigger warnings" thing. One person's "patronising" is another's "thank god I steeled myself before going past that." Something I found a bit excessive about that thread: individual comments erratically headed with their own warnings. The OP warning and content should be enough, surely?