Steam Reviews, "How to Properly Rate Them"

This is a pet peeve of mine, and I'm in the minority here, but no one uses the 'Steam Review Rating' mechanic properly.
It's very simple. The question being asked is "Was this review helpful?"

It doesn't ask "Do you agree with this person's opinion?" Everyone however uses the 'Thumbs Up / Thumbs Down' mechanic as if this is the question being asked, when it's not.

I've noticed a distinct trend where you label your review as "I got a complimentary copy of this game from the developer/publisher," and the review gets down voted to hell.
The same review can lack this tidbit and fare normally.

Do people have that much jealousy that I got the game for "free" and you had to pay for it? Is it it that they believe me to have bias?
Or, of course, the underlying question... Is it that they just don't agree with my opinion?

No matter the answer, people are using the voting system incorrectly. Was my review helpful? If it wasn't, tell me why.