This may perhaps reflect the different professional subcultures we're around, but IME "people who depend on tech" are _less_ prone to this (not necessarily the rabid fanboying but the equivalent effect). I think you're underestimating the effect that an unwillingness to do (relatively) in-depth research has on the purchasing decisions of "normal consumers". I.e., "wanting what they need to get done" is a wonderful wish, but it's somewhat meaningless when decoupled from knowing the differences/capabilities of each device. I don't think it's controversial to say that normal consumers put much much more faith in the wisdom of the crowds, and (if they can afford it), Apple products are the beginning and end of their search. The fact that "Android" or even "high-end Android" isn't a cohesive brand to the casual observer means that iPhones seem like a plurality of their cursory data set, even when it's not the majority (which, at least in the US, is pretty often).
Even in 2015, I have people asking me in slightly shocked tones why I don't use an iPhone, and their certainty is always based entirely on social proof (they generally have no knowledge about whatever is I happen to be using).
I cannot count the amount of times I have experienced this phenomena. A couple of years ago, when I first got an android phone, I remember someone say "Ha, you don't have an iPhone, your poor!"... the content of the comment didn't really disturb me, what did was the reasoning which lead the person to generate such a perspective.
Care to break down Apple vs. Microsoft's revenues in tablets? I can't imagine it's within two orders of magnitude, at which point I'd hardly say that Microsoft counts as competition. But maybe I'm wrong about the numbers.
(Granted, you said "pro tablets". I doubt we can get numbers on that, but I think the relevant distinction is "tablets used for work" rather than "tablets with XYZ specs", and in that space too I suspect without data that Apple is far and beyond the leader in terms of revenue.)
Outside of Microsoft (disclosure: MS employee), I don't see much competition for Apple in the innovative premium tablet space. They still execute well in the phone space, watch seems to be shaping up fine, they are still the only PC maker that is known for producing PCs that can last. The costs don't seem too off from the competition, unless we are talking about Xiaomi or Lenovo, but then the tradeoffs are obvious (no longer in the premium space).
I do see Apple slowing down a bit in innovation. I mean, if iPad Pro was released last year (stylus, yeh!), I might have bought it, but the Surface 3 came out instead, which is quite decent (I won't go SP3 because of the fan). But Apple is still executing well, they aren't making many mistakes. They have built up a loyal fanbase and haven't done anything to betray them yet.
People who depend on tech are usually about the shiny more than normal consumers, who just want to get what they need done. The rabid irrational Apple fanboy isn't grandma, no, it is the young kid working in tech.