I'd agree that it's good to see 'extreme processing' so that you can understand what the different processes do and also so that you can make choices about whether to deliberately leave your images natural looking or to push the effects side.
From time spent wading through some of the photo groups on facebook & elsewhere, very often those beautiful 'natural' photos that skilled toggers appreciate will get overlooked, while hideously gaudy or hugely over-cooked HDR shots get all the attention. Target market & all that: I think a skill little discussed in processing is knowing what will please the people to whom you will present the images.