How many words do you think the entire web, as crawled by Google, has?
The average quality is going to be lower, of course.
Here's one discussion over over ten thousand words: https://en.m.wikipedia.org/wiki/Wikipedia:Village_pump_(poli...
The least interesting thing about Mexican American War is what type of dash you use between Mexican and American. There are over twenty thousand words about that dash on wiki meta.
15,000 words would be okay if at the end of it there was some kind of consensus, or something that could be tramsfered to different articles.
The future people are going to have a skewed image of us if they think meta wiki is representative.