Jack, you and I (and I'm sure I'm not alone) have been discussing this issue on and off for the better part of several years now, and as a third party provider of display profiling solutions, your frustration with it is totally understandable. And as you say, it doesn't appear to be getting any better.
Under the circumstances, what consumers really need is a data base indicating what combinations of stuff work with your software and which don't. At one time some years ago you did have such a page on your website, but I can't find it any longer. Of course, there is a very large universe of displays, graphics cards and OS system versions out there, so no-one can seriously expect that you yourselves would have the means and resources to test it all - impossible - and then there are potential liability issues involved depending on what you claim or don't claim. But there is a way of doing this that gets around both issues: create a page on yourt website which simply collects and displays users' experience in a retrievable format. It would be a four-column table: (1) O/S version, (2) Display Model, (3) Graphics Card and (4) Result (DDC works or doesn't). Each line of the table would be filled by a user who has tried their combination of stuff and found it works or doesn't work. You publish it taking no liability for what people send for posting there - its their opinions based on their outcomes. This would serve two purposes: (i) it would pre-advise people what they should consider buying or not buying if they hope to get DDC compliance with your software, and (ii) it would create pressure on display and card manufacturers to achieve compliance by providing you with the necessary SDKs. Not only you, but other profiling solution vendors such as BasicColor should do likewise. Consumers need some way of wading through this "train wreck" and finding the survivors, if I can borrow from your apt analogy.