One of the most important things with computers is upgradability. Why spend $2000 for a computer only for it to no longer have the minimum requirements needed 3-5 years from now, and then shell out another $2000. It's a waste of money, and resources (so much for environmental sustainability). You are the type of customer that will just shell out money without looking into cheaper alternatives such as upgradings part on a slightly older but still perfectly useable computer.
In any case, does this concern iFixit's profit line? Yes, of course, they are a business. But you make it sound as though that they are a self-serving business that provide absolutely no positive service for consumer, when that is not the case at all. Their repair guides are extremely useful (which are free and publicly available) and have helped me more than a dozen times in repairing and upgrading my various computers over the years. Oh, and for the record, what does Apple provide for self-servicing your Apple device? Nothing, nada. Apple's technician guides are not publicly distributed (unless you know how to find it online) and the funny thing is there is nothing that is rocket science in those books. Let's just say that if you can build Legos, you can upgrade a computer easily.
And when your warranty runs out and your trackpad breaks down? Should you really have Apple charge you $200 for the repair, when you can do it yourself for $30 by finding the part on eBay and using a little common sense?
If there is any company that is only concerning their own profit-margins without any net benefit to the user, it's Apple. It only benefits them by making Apple computers not upgradable because then it coerces the consumer to buy a new computer. All for what? A microscopic .000001" reduction in thickness that you can't even notice?
Look at the Macbook Pro Retina, which is the worst computer in terms of upgradability. Once the battery craps out (which Applecare won't cover), you have to spend $200 to get it upgraded, and if you did it yourself it would cost $500. Before that model, even the Macbook Pros were considered "unupgradable" but in reality, all you had to do was remove the lid, and simply unplug the old battery with a new one (which goes for $50 brand new on eBay versus from Apple which charges $130!).
tl;dr - Don't blame iFixit, they're providing a valuable service to consumers that Apple, selfishly and deliberately, is hindering. If Apple makes their future Macbook Pros unupgradable (i.e. RAM, Hard Drive, and most importantly the battery), then I will choose not to buy another Macbook and go back to Windows (which I haven't done in 8 years now).