The problem is that it is often possible to solve the problem for (your) future, but you cannot get rid of the existing large files (if only for legacy reasons).

One example: A Git repository that I created contained files that are above GitHub's file size limits. The reason was a bad design in my program. I could fix this design mistake, so that all files in the current revision of my Git repository are now "small". But I still cannot use GitHub because some old commit still contains these large files. So, I use(d) BitBucket instead of GitHub.