kitekrazy1
I'd bet people who make a lot of money off their music only change DAWs because they exhausted their needs before moving on. I'm sure there are DAWs that can do more than Pro Tools but I doubt any engineer is going to switch because the familiarity is right there. Time is money for some and that excludes learning another DAW.
As it happens, most, maybe all DAWs can do more than ProTools once you go beyond the capabilities of e.g. Garagebend or some of the "introductory" versions of other DAWs. Especially regarding MIDI, where ProTools was well behind the curve for a long time. The first 64bit DAW was SOnar, not ProTools, and ProTools has limits in some areas that other's don't. I think you're quite right that the main reason many studios have hung on to Pro Tools is familiarity. Another factor, less important now perhaps, is that until relatively recently ProTools only worked with very specific and very expensive hardware but because of that there was a high degree of certainty it would work and just in case it didn't you took out a support contract. So once that investment was made it made sense to get the maximum value out of it.
ProTools was also very early into the market, and promised a workflow familiar to engineers used to working with tape. So many studios chose it when shifting from tape to digital, or even while still recording to tape but wanting to be able to do non-destructive editing by copying the tape into PT, working on the audio then re-recording it to tape.
Which in turn lead to ProTools becoming a de-facto "industry standard" and some musicians even now mistakenly thinking a studio isn't "pro" if it doesn't use ProTools.
As for hardware compatability with DAWs, outside Avid stuff for Pro Tools and some of the dedicated Live controllers there's sometimes quirks and workarounds involved. Logic, for example, can handle most things easily enough except 12-bit MIDI NRPNs which are handled horribly in comparision to Sonar.
But if a hardware manufacturer says "this product is 100% plug-and-play compatible with DAW X" and it isn't, that's the fault of the hardware manufacturer, not the fault of the DAW builder. Sure, Sonar could do with some work on the controller side of things, but even then there'll still be "100% Mackie compatible" controllers which aren't, or "Built for DAW X" hardware that needs work-arounds and has bugged firmware. Which is why it's always a good idea to research what hardware can do in the real wrld before parting with money.
Sometimes spotting what the manufacturer doesn't say can be more important than what they do say as well.