I do scoop lo mids as a way to improve bottom clarity, since the dreaded 200~400 range can make the bass sounds really muddy by itself (and particularly on some problematic room acoustics) and also clear some room to other instruments in the mix (in fact, almost every other voices in a band needs some space between 100~400 since "our lower mids" can be where their fundamentals have to sit in).
Rockers used the smiley graphic Eq for ages, but this is not exactly "scooped mid" (is more like no mids at all). Seems to me that this is due to gear misuse, too. But it clearly helps to get the bass away from guitar path, though. Now, we are seeing rock guitar tuning getting increasely low, so maybe bassists are loosing too much mids for "our sake". Not intending to be disrespectfull, bass can ends sounding almost as a kick drum (just thud and kick) on some metal records.
Slappers also need to clear some lo mids to make lows more clear and defined, the question is wich mid will be tamed (since 200Hz is very different from 400Hz or 800Hz or 1600Hz, and each one to the others) and to what stance, if you don't want to end with no meat in your bass bones.
