I'm not sure. I think part of the problem is that Linux still uses entropy estimation. This is also one of the issues I have with the proposed replacement[1][2] for Linux's current CSPRNG implementation since it still retains entropy estimations.

[1] https://lwn.net/Articles/684568/

[2] https://news.ycombinator.com/item?id=11561340 (HN thread for [1])