[JimmXinu]

Originally Posted by ownedbycats

They actually did! Limit of 75 tags now, after that incident with the story using literally thousands of tags and outright crashing browsers. But older works with more than that will keep the tags (until the author tries to update, then it'll make them delete some).

I did not know that. A quick google finds the AO3 announcements.

Why 75 tags?

We looked at all the works on the Archive and determined that:

the average number of tags per work is 17,
the most common number of tags per work is 11, and
less than 0.5% of works have more than 75 tags.

A limit of 75 total fandom, character, relationship, and additional tags per work will provide the vast majority of creators with enough space to describe the content of their works while also keeping work blurbs to a manageable size.