HDR isn't a look, it just means high dynamic range.
Most digital cameras capture more than 8bit per channel, most are about 12bpc iirc (my D70s is and it's fairly old now, newer ones may be even more)
The issue is our computer digital displays stop at about 6-10bits of colour display, depending on model, so it's how we rationalise the wider range we can capture, even with a digital camera, onto our display range of ~ 255 levels of colour intensity per channel.
That is tone mapping.
Tone mapping has ALWAYS been around, gamma correction is a type of tone mapping.
Load a RAW in 12bit per channel from the camera, and it's tone-mapped on the SLR's little display, then it's tone mapped in photoshop, and by the gfx software for monitor gamma correction.
Film was 'tone mapped' when you developed the photos. You could get some fairly funky looking effects with it!
I'm all for using more stops of exposure to get an image that you can see with your eye, but the camera limited to maybe 4-6 stops can't, but to just use the effect on raw images, and tone-map something to look a bit funky for no other reason than you can, seems a bit pants to me.
Lets put it this way, Ansel Adams didn't need "HDR" to take good pictures... and half the pictures I see that are HDR, even good ones, didn't NEED to be HDR'd... chances are while they were taking their bracketed shots, they had a perfectly nice exposure in there already anyway
Dave