[dennisw]

Also consider the plight of the PC user with Windows XP installed. If they want to upgrade to Windows 7, which is actually a pretty decent operating system despite still being saddled with such land mines as the dreaded Registry, they are forced to do a clean install. By clean, I mean wiping the hard drive after backing up your stuff to an external drive. Microsoft’s migration utility is limited to your own documents, not applications, such it’s of little help in dealing with the real issues, which involve reinstalling all your apps and hoping all your settings will still work even if they are restored to the same location on your PC’s drive. Yes, that’s not a given

Clean installs were never very difficult. But with the advent of external hard drives there is no excuse and you don't have to be that smart. 
I can think of one legitimate excuse
Many computers today are sold with huge hard drives that are un-partitioned except for a recovery partition
Therefore if someone fills up a 500gb-1000gb hard drive I can see where it can be an imposition to back up all that data without making mistakes onto an external. Then putting all or most back on the hard drive after the re-format or upgrade

The obvious solution is to have a partition for your operating system. For Vista/Windows 7 I allow 40-50gb on a 500gb or larger hard drive. Less on a smaller one

[Mind-numbed Robot]

Your explanation of the ease of installing Windows 7 on a PC with XP is a fine example of what this article is saying rather than rebutting it.

If a person needs an external drive for backup isn’t that a PC tax? You don’t need it for a Mac.

If a novice or non-technical person owned a PC and wanted to do the upgrade as you describe wouldn’t they need someone to help? Most have no idea what partitioning a drive even means. Aren’t they likely to have to pay for the help? Isn’t that a PC tax? It is not necessary on a Mac, unless of course you are doing the MS OS upgrade on a Mac.