This is always a tricky situation; the mechanisms involved and potential issues caused are rarely thought through.
Not that there's anything wrong with wanting to help, of course not - but anonymity is often very valuable to someone and not something that should be stepped on.
Supposing you were anonymously sharing something upsetting and very personal on WP but unknown to you, your ISP had been contacted with the intention of either asking them to somehow step in and help, or asked to provide your street address.
It's unlikely any ISP would want to step into the legal minefield of contacting someone (who exactly - International Rescue?) to turn up at the member's home and... bang on the door demanding to be let in to help? Explain to shocked parents about trauma they had no idea was occurring under their roof?
And who would fund such an enterprise, even if it could be enacted?
Who would be responsible if such an intervention backfired badly and made an upsetting situation even worse - suicidal, perhaps?
It's even more unlikely an ISP would hand over confidential account information to some stranger on the Internet on the premise that they want to help or organize help to a customer of theirs - but even if they did, then what? It seems we're at the same "bang on the door"/costing scenario as above.
Asking a WP member who may well be a professional psychologist/therapist/counselor is also fraught with issues.
Professionally and ethically they can't be expected to step in and somehow convince a member to make use of their services over an Internet forum interface. If they wish to help personally it has to be a decision they make alone, like any other member responding to a thread and likewise, it's up to the intended recipient of the help whether they want to accept any of it.
WP is a membership-driven social support site which does not, and in its current form can not, provide any form of professional services.
Members seeking help should be directed to local professional services which might be of use, if they're happy to provide location information - but if not, only general advice or pointers can be provided.
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Giraffe: a ruminant with a view.