snoyberg/http-conduit — comment on commit 8e4a036593c36ecf5cb97f49c98c9a268a45af94
File: Network/HTTP/Conduit/Manager.hs line 163
By snoyberg:

Yes: someone has an existing `ResourceT` that they're running in. For example, they want to make a few connections inside a WAI response, but (for whatever reason) don't feel like keeping a manager for the whole app.

Or a better long-term example. Let's say someone else writes another package that has another manager-like think (call it a frobnicator). If they only provided withFrob, and we only provided withManager, users would be required to have two `ResourceT`s to use both libraries. Throw in some `resourceForkIO` fun to the mix, and you've got some major bugs too.