Most of the time, they seem to needlessly bloat their wiki page with walls of text, and are often unneeded if one knows what the tags are by looking at the image in question. For example, I do not even know who the character in post #7366624 and post #6031168 is when I uploaded the posts, but even though I can't look up the character's wiki, I never struggled at all with tagging up her appearance since I'm just going by what I see in the image, making the character's tag list describing her appearance unneccesary.
These are often seem to be used as crutches for people to tag the character's physical appearance (especially when the "wiki tag" feature was still active), even though it is largely unnecessary if (as mentioned before) you're tagging based on what you see in the image. Additionally, these "typical tag" sections are sometimes written by users who have no clue how to use certain tags correctly, which leads to the wiki misleading other users into misusing tags (ie. Raiden and Shenhe's wiki having braided ponytail in their "tagging" section of their wiki, or the jackets of some vtubers being incorrectly called "off-shoulder jackets", resulting in mistags).
The current wiki format for Shenhe (as an example) is simplified to just describing who she is and has the "typical tags" list removed, which I think all character pages should follow the same format. Additionally, with the addition of adding thumbnails to wiki pages, we no longer need a dump of the character's "typical tags" to give an idea of what their "default" appearance looks like.
Updated