I really apologise for any offence this causes, but I don't understand the vitriol here. Clearly there are children for whom vaccination is contra-indicated, because they have siblings who have been vaccine-damaged, or perhaps for other reasons too. And very clearly this is an extremely sensitive issue for those people and we should all respect the decisions they take. I wouldn't for a monent doubt the decisions made by parents in that position.
But it is also a reasonable opinion to believe that there is a public interest in most children being vaccinated, and, arguably, that there is an obligation on parents whose children aren't contra-indicated for vaccination to have their children vaccinated.
I didn't read the OP as targetting people who have very good reason not to vaccinate. I saw her points as being directed more generally, and therefore as making pretty much the same points as are standardly made within the NHS as part of their recommendation that most children should be vaccinated.
Perhaps there is a backstory here with this poster that I don't know about, but in the absence of a backstory the impression I get is that posters aren't tolerating a statement on MN of quite a mainstream opinion.