Nothing wrong with it but learning to work within the limits of your hardware is a part of using a computer, so closing the odd app when not in use is a sensible way of keeping your computing experience fast and anyone with an ssd installed has almost instant app opening making this hardly a chore. This seems to be a foreign concept to younger people who never shut anything down and then just moan that their hardware is not good enough, when they could just close an app they haven't used in the last 2 days. That at least is what I have seen with the teenagers in my house.
12 browser windows is not that many and indeed I have seen posts on here of people with hundreds of browser tabs open, each running flash video often using chrome a massive resource hog itself, then they wonder why their photoshop app is running a bit slow, if your workflow doesn't suit your hardware then you either change your workflow or your hardware. When that choice is forced through general laziness or just not thinking about what you are doing and a workflow change is not going to have a negative effect on your productivity (or possibly a positive effect from some of the things I have seen) then change your workflow, its the quickest easiest and cheapest way of making the most out of your hardware and seems to have been utterly forgotten over the last decade as a sensible and viable option.
