Well, a couple reasons, really. A year or so ago I came very close to replacing my Pentax Ist D with a D70/s so that I'd have just one lens system. The D70 and the D2H would have been good companions. I wound up keeping the Pentax instead (long story).
Just a couple weeks ago my wife got her first camera, which was a good used D70. I finally had a chance to play with it for more than just a bit at the store and I'm quite impressed with it. It's almost the exact same size as the D200 but much lighter (good for my wife who thinks the D200 and especially the D2H are too heavy). The photos are sharp and quite good right out of the camera.
Both of those reasons have me lurking a bit more than I did previously in the D70/D50 forums, but I've always enjoyed reading the posts. It's amazing what you can learn in general, even if you use a different camera model.

Plus, there are a lot of great photographers on this forum. Great pictures are certainly not limited to the "high end" camera forums. Just further shows it's the photographer, not the equipment, that make a photo special.
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A camera is just a tool - no matter how much one loves it.