Naw, I don't think that's what he means; the idea is that a DSLR is in an entirely different class from prosumers and P&S.
If you ask me, the main difference is indeed, inability to change lenses and also, the fact that sensor size in prosumer/P&S is smaller than DSLR - meaning usually inferior noise performance. For prosumer, the amount of manual control tends to be almost there for basic levels of control at least. So it is a good way of introduction into the world of photography if you want to eventually get in deeper. And after all, prosumer is a lot more convenient in the sense that you don't have to lug a few lenses around on photoshoots, and worry about cleaning and all that. But then again, any P&S with manual control (ie. maybe IXUS 800 IS) would also provide that. Without the long zoom, though.
But anyways, just stick with the prosumer for now, unless you're absolutely sure you really want to commit to DSLR lor! Hope I helped with the queries - do some reading up and you can find out more!