[...]I guess one day if they come up with color control only for out of gamut colors then that would be a good workflow?
I think that's a bit too simple of a solution. The best solution will vary based on the image itself, and the goals of producing the output. We have two common rendering intents that handle out of gamut colours in different ways: perceptual compresses the whole gamut to preserve subtle details at the expense of lesser overall accuracy of colour; while relative colorimetric preserves overall accuracy at the expense of clipping out of gamut colours thus wiping out detail. Sometimes one approach is okay, sometimes the other is better. It depends.
In the same way, if you chose to do manual work in post to adjust the image prior to letting the rendering intent tackle things, sometimes you might want to bring down only the out of gamut colours. Other times you might want to bring down a broader range of colours including some that are in gamut, in order to preserve subtle surrounding details and "feather" the adjustment more gracefully.
When I do these kinds of edits, saturation usually is the last adjustment I resort to. I usually start with tonality adjustments in one form or another -- curves, luminosity. Or other types of non-saturation adjustments like hue or density tweaks. The adjustments I make are guided by soft-proofing initially, but not by soft-proofing in Photoshop for cases I really care about. If I really want to see what's going on, I use Gamutvision (a Windows tool) which provides more comprehensive, detailed and useful information about differences between image colour and rendered output colour.
Whatever types of adjustments I'm using, I would rarely-to-never hit the entire image with a global adjustment. Typically I would make changes in selective regions (including specific channels) of the image, but covering a somewhat broader range of colours than just those that are strictly out of gamut. I'm usually trying to strike a balance between detail and colour accuracy; where I put the fulcrum for achieving that balance may vary from one image or output purpose to another.
And of course, like Andrew says, I don't go to this effort for any images I post at low res to the web. Those cases just aren't worth it. When I tackle this issue manually, it's for prints that I really want to dial in.