This isn't just about NFS timeouts. Try playing a movie from a rotational disk while simultaneously doing high-volume writes. You will get frequent pauses in your video because the write buffer size is so large that a single writeback will cause the video buffer to drain empty.

On my desktop with 32GB ram, I can even get audio to skip when ripping DVD's to disk. That's because practically the entire movie fits into ram before Linux decides to start the writeback process, and that writeback process will hog the disk for almost a minute. Or it used to, until I reduced the buffer size by a full order of magnitude.

This is just another sad example of buffer bloat: the inability to tune data buffers to the capacity of the underlying stream.