It's a bad habit to do too much, or all editing in ACR. ACR applies your tweeks big bang, meaning it applies them to the ENTIRE composition. Sometimes this is ok, many times not okay.
I only do exposure and white balance tweeks in ACR, and NEVER anything else.
I apply my tweeks surgically in PhotoShop, using layers and masks as required, and all this can be done very fast.
Editing in ACR is often the worse place to do them, and for the reasons I stated...better to do it surgically in PS or whatever program you use to edit converted raw files.
I don't agree that it is a 'bad habit', that's a pretty strong judgment. I think if you like to use PS to do your adjustments, that is a preference, rather, than the 'right way' to do things.
ACR has an adjustment brush which allows you to make localized corrections and adjustments, much like masked adjustment layers in PS. I think the clone tools work wonderfully. A professional work flow often contains three rounds of sharpening and the first one occurs out of the camera--many feel ACR's sharpening tool is exemplary. I love the graduated filter tool and use it all the time. I'm not defending ACR, but I'm trying to make a point that ACR definitely has uses beyond WB and exposure in a professional workflow. I feel I am a somewhat advanced Photoshop user but personally I try to do as much as possible in ACR or Lightroom.