No one needs to do the assistive technology workaround. Both the upgrade in place and the clean install of 10 both work today. If you have a working 7 or 8 system you can do the upgrade without the key. I always recommend doing a clean install unless you have a compelling reason not to. If you have the old key, you can download the media creation tool from MS, install a clean version, enter your old key when prompted, and it will activate fine. If you don’t have the key, you can use Magic Jelly Bean to retrieve the old Windows key from any working system. MS has no intention of stopping the upgrades because they want as many people as possible on a common version.
I have no idea why redmed’s install didn’t activate. I’ve done tons of these, as recently as this weekend. You do have to be careful about versions. If you have a home key, you need to install home. Business to business. I’ve seen 32 bit keys activate with 64 bit, but also seen them fail.