Can you give any examples of this? You may be over-generalizing. Most of their products don't even have replaceable parts. Are you sure their reasons aren't legitimate?
RAM from Apple is certainly expensive enough that almost no one recommends it. They also tend to nickle-and-dime you on accessories like converter cables.
"Their products are deliberately engineered to make it painful to seek affordable alternatives when you need new parts."
Some of apples products have RAM directly soldered to the motherboard. This has legitimate engineering trade-offs. Of the ones that don't do this: Are there any that deliberately void compatibility with alternatives. It looks like most of their cables have alternatives too. Their stuff is expensive sure. But are they deliberately locking you into using their accessories?
So basically, you are griping because Apple hasn't chosen to be a mass seller of RAM upgrades who keeps large stocks and is willing to sell it for very small profit margins.
Heard of damning with faint praise? I'd say this amounts to praising with faint damn.
Whatever. I was just pointing out that Apple sells things that are much more expensive than what you get elsewhere. If you choose to read more into it than that, then go ahead and knock yourself out.
They also sell things, like the Macbook Air or iPad, that are much less expensive than what you get elsewhere (when you try to get an equivalently spec'd device).
Given that their devices cost less, I can forgive them the convenience cost of an in-store RAM upgrade when they're helping my Mom upgrade RAM or HDD in her beloved 15" Macbook from years ago that still works a treat. Most customers are not really the NewEgg type.
To grandparent's point about costs of low turnover stock, these parts cost more for much better reasons than Jiffy Lube oil costs more, yet most people prefer Jiffy Lube except mechanics or DIYers.
They also sell things, like the Macbook Air or iPad, that are much less expensive than what you get elsewhere (when you try to get an equivalently spec'd device).
Perhaps this is true in America but I'm pretty sure it's not in many other places. I recently looked around for a laptop to put Windows7 on and while it was discouraging to see the quality of the laptops that were available (compared, not just to a MacBook but to other laptops that existed 3 years ago) they were significantly cheaper and higher spec'd than a MacBook.