DISCLAIMER: Not sure there is a good answer to this one, but I'll take a stab at it. Also, I'm not attempting to defend the practice, merely explain it. Like you, I think its annoying that people can't put the posts where they belong, but I digress.
RPi is at its heart a tinkerers paradise, halfway between a solid Linux box and micro-controller for all your sensors and blinkies. The community as a whole tends to be filled with the kinds of people that believe in the value of cracking the case open, figuring out how things work and such.
The Maker mindset has become really popular among hobbyists in the last few years. So much so, that people that don't normally fall into the category themselves are learning about them. These 'near-hobbyists' don't know the difference between an Arduino and Raspberry Pi, but do know that the users and gurus of both probably know how to wield a soldering iron, de-gluing bag, and spudger.
Here's the connection, someone that knows how to do these things might know how to fix the busted apples, and for less than the apple store would charge for the fix. Since iPhones can be used with RPis in certain ways or with software to control a project or display output from a project, that is the 'infection vector' I think.
As to why its iPhones over 'Droid phones, I couldn't offer an opinion other than most Android phones are not as engineered with special hardware to make it hard for the end user to take it apart. Pentalobe, I'm looking at you...
The post you mentioned, I saw and flagged it as soon as I saw it, and if memory serves it was within 5 minutes of being posted. I also dropped a comment for the user, thinking that they might just need a little point in a better direction. Call me soft-hearted, but I got the impression the user was new to SE in general, young, and probably trying to find help after spending a little bit of time googling for answers and finding a lot of places where the results boil down to "Take it here and pay $$$"
So, take the good with the bad, SE sites are showing up in google results more often, and that brings in the ignorant, the desperate, and the trash. But dealing with cruft is nothing new. StackExchange in general handles it about as effectively as FidoNET or RelayNET ever did. Of course it could be worse, SE could have gone the Usenet route to oblivion.