This is true. Whatever works and leaves as much original paint as possible should be used.
A lot depends on the pre-spray prep the person did before overspraying. Old paint, especially old baked-on paint will tend to be stable while the new paint won't adhere very well to it. I've had no luck with gasolene, kerosene or denatured alcohol when I tried to strip spray paint. I've had some luck with Xylene and MEK. Acetone will also work but is hard to control and will pull original paint. It also evaporates very quickly. I've had mixed luck with oven cleaner as well. Regular oven cleaner will work but, again is hard to control and will pull original paint. I've had no luck with environmentally-friendly oven cleaner at all.
The last time I did this, I pulled out a 1980s-era bottle of Tru-Value "Stripz 'Em" paint stripper and tried that. It worked very well and pulled spray paint with one wipe. It was like dusting the bike, but it was removing spray paint rather than dust - one wipe and it was back to original paint. Again, in this case there had been no real prep for the spray, so it worked out well. The stripper can and will absolutely pull original paint if you get too aggressive though. I have no idea if this stuff is still sold, but I wish I had tried it sooner because it seems the best of any approach I have tried. I put a tiny amount on a rag and start to act as if I am "dusting" the bike. It beats spraying stuff with oven cleaner and hoping I have not over estimated the pickling time.
I will add though that I tend to avoid bikes where this kind of work is needed in any great quantity. Stripping spray paint is one of my least favorite things.