I think you raise some good points, and in my view a lot comes down to the goals and expectations of the hobbyists.
Let's be honest, it is a very normal thing to look up to those who are perceived be amongst the best at something and want to emulate their work. Often this means looking up to those who are considered 'professionals', and by that I mean those who make a real living out of it. This applies to sports stars, it applies the musicians, and yes, it applies to photographers.
Now by wanting to emulate, many amateurs rely on equipment (often to their detriment). To a professional sports photographer, frankly, the art is the least of their interests (though they may care in their personal, unpaid photography). If you rely on capturing 'the shot' from a fast paced event, be it sports, air shows or whatever, you will want every advantage you can get, because every advantage means more food on the table (as it were) - faster, more accurate AF and faster frame rates count, it may not guarantee the shot, it may not even double your chances, but that increase is critical when it is the difference between being paid and not. Now, being professionals, they have honed their skills through experience, lots and lots of experience, and the equipment works hand in hand with that experience to produce results. For amateurs, they see great photos (never mind the thousand that didn't make the cut), they see the expensive gear, and think that gear = results. Now for some (the gear heads) this may be what gives them the joy of their hobby - never underestimate the desire of a great number of people who just want to own 'the best'. For others, they put their poor results down to their gear, and with no frame of reference this makes sense to them - when they get the gear they know works (because they see the professionals use it) they are content, no longer is the gear the possible limitation - never mind that the professionals would still get stunning results with the 'lesser' gear (at the possible cost of their competitive edge).
Then we get back to goals. The above is more or less my experience with those who look up to most 'professional' photographers, those paid to document something. If you look at those who admire photographers who are more 'artsy', you see a different breed of hobbyist - I don't think any lomography shooter ever wasted time debating AF performance online (they would substitute with something equally inane, but more in line with their preference).
It seems that the former type of photographic hobbyist greatly outnumbers the later, and I think this is down to a few things - first, many more photographers make a living documenting than by being artistic (starving is almost a way of life for artists). Second, and I think this is more important, it is much easier to measure the technical stuff - sharpness and be measured, so can focus, and motion blur. Plenty of really good photos are technically crap (out of focus, crappy optics, loads of grain, bad composition, bad lighting, poorly exposed) but they are still good photos because they capture something, but that something is near impossible to measure. For an amateur, if you cannot measure, how can you track your progress? Much better to know you are advancing your skills because you photos are measurably better then by feeling you photos are better. Neither is really right or wrong, but it's face it, we have all seen the attractiveness of one path or the other.
So to bring it back to the actual topic of Pentax's AF, the hobbyist who desires technical perfection sees their idolised professionals all out at the game/air show with Canon and Nikon gear, and so in their mind it MUST be much better. Is it better? Yes, marginally. The AF is slightly faster, the tracking has a more refined algorithm, the lens motors are a little quicker. Does this matter? To the professional, yes - they don't want the phrase 'starving sports photographer' to enter common usage like 'starving artist' has, so every little advantage counts, and frankly, they have the skills to back it up, so good on them. For the hobbyist? No, probably not. There may be some who push against the limits of some gear in some cases, but the majority would not find a difference between their performance with Pentax and Canon/Nikon outside of their own minds.
Finally, should we care? Probably not. If someone wants to spend upwards of $10,000 on a top end body and trinity of f2.8 zooms for an occasional Facebook picture (but otherwise leaves the gear in the cupboard as it is frustrating) so be it. Be happy in your own mind. And I say that despite being involved on another forum where if you don't have a FF body with the holy trinity you are a nothing is the general attitude of the self appointed experts (so yes, they annoy me to). I just wish they would be as happy with their choices as I am with mine. That they, or anyone, needs to constantly talk down the needs, goals and choices of someone else says all you need to know about them.
