She specifically used "quotes" supposedly made by MNetters yet linked to a thread which didn't have those "quotes"
You realise broadsheet journalists don’t upload their own articles, sub-edit them themselves, write the headline and then add the links themselves too? 
“She” hasn’t linked to anything. She just wrote her article, emailed it in to the office and someone else subbed it, headlined it, and added the illustrative and explanatory links that is part of online Guardian house style. The links are an extra. A website feature. They’re not integral to the journalist’s work.
The half paragraph from her piece regarding MNers was;
“Hancock-averse contributors to Mumsnet could be found, last week, trying to source his wife’s outfits, admiring the excellent sunglasses, her hair and the dress sense his shitty behaviour had also, by way of a bonus, offered for thorough analysis. Didn’t she, some thought, look just too good, considering? “She knows exactly what she’s doing.”
So the journalist has referenced several things that were said on Mumsnet, reached a slightly strange opinion about them and said so. That’s fine. It’s her job. That’s all she had to do. Linking is not part of her job, and bizarre is exactly the right word for your demand that every reference in her column needs a linked url.
It is frightening how many people are clueless about the norms and conventions of the media.