Is the ability to disable flow control really needed?

Reading the "Ending Flow Control" section of the spec (3.8.9.4:
http://http2.github.io/http2-spec/#EndFlowControl ), I'm wondering if we
even need the ability to disable flow control at all.

First, it's not clear what disabling flow control means in that section.
Does it apply only one way (i.e., letting the other end know that they're
free to send data at any time) or both ways (i.e., being able to send data
at any time)? I'm assuming it's not the latter, as that would be dangerous
for the other end, but perhaps the language should be clarified.

My main concern is that I can't think of a situation where setting a really
high flow control window wouldn't suffice to effectively disable flow
control. Granted, it's not exactly the same thing, but I can't imagine that
keeping track of the received window size would be onerous enough that
adding this other special mode would be worth it. And if it is onerous for
some implementation, I would have low confidence that it would get the
tracking of the send window size right, either.

I searched, but I may have missed some earlier discussion on this -- feel
free to point me to it. Thoughts?

-- Fred