because sometimes you dont know what malware can be in various links etc
Embedding malware in web links is very 2010. Modern browsers are basically immune to it, so people don't do it.
Plus several hundred people have already clicked through the link (starting with the Mumsnet preview window, which "clicks" it automatically), and over 100 have reacted to the story, and nobody has come back to report anything untoward.
Plus you can inspect the link (hover over it) and see that it goes to tes dot com, which you can then look up on Google and see is a legitimate website.
So really, don't worry about clicking a link that someone posts here. It would be an incredibly inefficient way to try and hack some random person's computer. 🙏