Not arguing your point, but Steam is not the issue
Just back up your Steam folder to another disk, reinstall your PC on the new disk and copy the folder back again. Log in, give your password and presto, your entire library is again available and useful.
Disk drives do not stop Steam from working. Changing motherboards do not stop Steam from working. Even upgrading the OS is generally not an issue for Steam. Just run the exe, log in and your files are there, ready to work.
I have changed HDDs, motherboards, video cards, reinstalled XP, installed Win 7 (32-bits) and so on and so forth, and every time I just launch Steam, log in and it works. The one time I had to reinstall my games (not Steam itself, just the games), was when I upgraded from Win 7/32 to Win 7/64.
If you stay on the same OS, you do not need to consider Steam as a liability. It is rather unique in that way.