Well, if recording MIDI from the controller, yes, for sure. Vouching for RB here.
If you have RB, you already have Powertracks and then some ..

Is RB a DAW? Well yes, it does most of what other DAWs do, and some things others can't, but it has its own rules/workflows.
If you are not already use to another DAW, you'll be fine.

I find that quite often, I don't really 'need' the other DAWs I have, RB does what I need, just a different workflow.

If trying to record Audio from a controller, you are going to have to learn Routing in any DAW.
The benefit of having Cakewalk (which is free BTW), is that you now also have the TTS-1 synth, which RB and other DAWS can use.
Peter Gannon (the 'PG' in PGMusic) made a 'No Brainer' post on obtaining this synth (recommending getting CW just to have it) so you can have a decent 'default synth'.
So I'm guessing a lot of the staff use it as a default synth also, but this is just conjecture on my part.

I have a few hardware synths with GM patch options, so I feel fine without it so far, but that's just me.
Basically, yes, if you have Realband, you do not need Powertracks at all (Realband development/updates happen before PT historically; PT gets the upgrades RB already has later in the year) .. again in recent history anyway.

I do not work here, but the benefits are still awesome
Make your sound your own!