The problem with IVF is that you need to find the right centroids.
And that doesn't work well if your data grow and mutate over time.
Splitting a centroid is a pretty complex issue.
As are clustering in an area. For example, let's assume that you hold StackOverflow questions & answers. Now you have a massive amount of additional data (> 25% of the existing dataset) that talks about Rust.
You either need to re-calculate the centroids globally, or find a good way to split.
The posting list are easy to use, but if you are unbalanced, it gets really bad.