It seems that rarely a step child or mum can do no wrong in many posters eyes.
Au contraire, the biological mother of my DSC (and I will use that term on this occasion because she had abandoned them at 6 and 27 months respectively and they had no clue who she was when she eventually reappeared more than a decade later), was deeply flawed. And that is the most I can really say about it precisely because she was their mother, however flawed, and I might be recognisable to my DSD, if she uses MN.
Until society helps and supports step mothers to deal with difficult situations, we will keep on seeing second marriages failing.
In my case (many cases), first marriage, but I take your point. The question is 'what type of help is helpful?'
My own take is that when you become a parent, the DCs needs have to come first and that also applies to DSC.
So while we might moan or chew the fat about a behavioural problem or an issue involving a (bio) child, and sympathise with others going through similar, we don't tend to suggest detaching, going no NC, letting someone else deal, sending the DC away to live with someone else...... and so the same applies to the DSC.
Most of the really horrendous step situations that get posted about are really dysfunctional marriages anyhow. A step family is only as good as the central relationship. One of my DSC had horrendous EBD, which got bad when his mother reappeared (and then re-vanished) but if our marriage had been 100%, we would have survived it.