When a user is not satisfied with how a product performs, they should be helped by the producer of that product.
Exactly... so contact Apple. Posting here won't get a response from Apple. If you don't want other users to try to help you, don't post here.
a warning should be provided.
What? You think a warning should be provided that sometimes things go wrong and you may need to seek help? Get real! What planet have you been living on? Have you never purchased any item of any kind before? Any product can have or develop a fault or not work exactly as expected. That's what guarantees, warranties and customer support is for. People have problems with cars, TVs, food, cameras, homes, everything on a daily basis. Do they all come with a warning?
Apple staff should follow this site and use their expertise so the rest of us don't have to guess what has to be done when a problem occurs.
It's not for you to say that Apple staff should follow this site. Apple provide extensive technical support articles on their support site, one-on-one support in their Apple Stores, and support over the phone - maybe you should use the avenues of support Apple provides, rather than coming to a clearly labelled user-to-user help forum and making demands that Apple should be here.
Hundreds and thousands of Apple customers help each other out on these forums everyday. And since these forums are worldwide and open 24 hours, often help is received much quicker than you would contacting Apple directly, due to opening hours, time zones, support queues etc.
However, sometimes there are problems that users alone cannot solve, and it is then that you should contact Apple directly for help.
Incidentally, I don't see many (any?) other customers with your specific problem, nor many people posting a solution for you (which would happen if it were common). As you already have iTunes running successfully on another computer you own, perhaps the problem is specifically with the one computer you're having problems on and not necessarily with the software? Nobody here knows what other crap you have on this malfunctioning PC or what hardware you've got. It's the nature of Windows PCs that they'll have problems - that's why the internet is full of Windows support sites and forums.
Otherwise we have to use the only weapon we have - stop buying their products.
Speak for yourself, not a collective "we". Stop buying Apple's products if you want. Nobody here cares what you buy. Always buy the best tools for the job, which you've already said an iPhone doesn't have a critical feature you want. However, also bear in mind that Apple consistently comes top for customer support and satisfaction in independent studies, so it doesn't mean you'll get better support from a different company - and all companies products can have problems.