One good reason is that one may want to keep certain web based images in a folder, "just for the record", and since LR is partly a catalogue, one may wish the folder to be tracked by LR, so that the images are accessible and visible. The OP doesn't, rightly, want to be bothered by these images on a day to day basis, and therefore wanted a way to disable the view of the web sub-folder. I don't see a workflow problem here.
The LR paradigm, as I understand it, is to produce final, baked versions of photographs only when they're needed, for printing or export.
There's no need at all to keep burned jpegs in LR's catalogue; the simpler and better approach is to keep the instructions needed to produce them again. The best way of doing that which occurs to me is to use virtual copies, which if they are stacked with the original images aren't visible but are readily available to re-produce the web jpegs as and when required. There may be others.
The workflow OFaaT describes strikes me as perfectly valid when only PS was available; but capable of improvement now he has LR available.
The trouble with turning off "show photos in subfolders" is that it applies throughout the catalogue and deprives him of something which is potentially pretty useful. Still, the beauty of options is that they're available to those who wish to use them. There's more than one way to skin a cat (I'm told).
Jeremy
