I think it depends on the story. Cause they aren't needed for every VRMMO story, and when they are used, sometimes they are used poorly.
I do think they are a good way to show an outsiders perceptive, especially since it is a game, and games usually have a lot of community chats and discourse going on in the background.
It can help flesh out the world, show what other characters are/can do, and even even introduce new elements into the story.
They can also just be good if they are entertaining. Most of the time that means funny, but as long as they are entertaining then that's a good enough reason to have them.
However, there are points against.
The least negative point, is that sometimes it just isn't necessary, for certain stories we don't need to learn about the world, and it would be better to just focus on the mc. This is more story thing though which is why its barely a negative
Now some actually negative points. They can be over done and repetitive. Some stories just have to many of these chapters, and it gets worse if the content in them is blame or boring.
A common bad use of them is "Praise/Reprimand the mc", having one or multiple of these isn't necessarily bad, even if it can be bland. But stories which tend to have these type of forum chapters tend to have them happen a lot.
So yeah, basically if they are done well and pace out appropriately they are a good support for the story. Sometimes they aren't needed, but it doesn't hurt to make one.
When they are done well, they can be some of the best parts of the story.
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