You obviously were not on MN at the time. Threads deleted in droves every day because of extreme racism.
Black posters being singled out for abuse and being stalked round the board, doxxed, and Meghan-bashers photoshopping fake DMs and bragging about it on other boards to try to get them banned.
Do you not remember there was a whole rival forum that started up that had Mumsnet in its name, that was created by banned Meghan-bashers (mainly banned due to using racial slurs) primarily as a place where they could hate on Meghan without any rules? And they would literally plan "raids" on MN, where they'd come back as Previously Banned Posters to attack and troll Meghan and Meghan fans, and coordinate ways to get Meghan fans banned?
There was one woman who openly bragged that she'd been banned from MN over a dozen times for things she said about Meghan, and that she kept creating new email accounts so that she could keep re-registering new accounts.
Many of the posters who were known as Meghan Haters circa 2018 had reputations for posting in every thread about black people or race issues they could find, and always being extremely goady. The same posters saying they hated Meghan, thought she was a narcissist and were praying Harry called off the wedding were also posting up a storm in BLM threads (calling BLM protestors "thugs" who should be in prison), in Ahmaud Arbery threads (saying he deserved to die), in white supremacists rally threads ("I don't agree with what they're saying but they have a right to free speech!), endless threads defending golliwogs and blackface.
Regular reference to conspiracy theories about Meghan being a sex worker.
Posters very very regularly name-changing and posting "I have a friend working in Hollywood/Buckingham Palace who told me all these terrible things about Meghan."
It was non-stop extremist hate from day one.