I think, the problem is that the scale is all on the positive side, but people are trying to use it to give negative rating. So naturally they readjust the scale, so that it has both, positive and negative sides, by "shifting" the zero of the scale. Now, where exactly does it go? Will 3 become 0, or is it 2 for some people, or maybe 4?
I know it's way too late in the game, but why can't the rating system be just a simple "good", "bad", "it's ok", or maybe even: :-(, :-|, :-)
I despise that sort of system. None of the choices ever seem to be appropriate for what I think or feel.
Star systems avoid inspiring this frustration in me by giving me the freedom to imagine labels that I think fit how I feel or think.
And in statistical circles, this is called survey bias (rating bias).
If you think a 4 is "awesome", and another person thinks that it means "pretty good", and this effect is widespread, it will result in a biased survey that is difficult to interpret.
I noticed a while ago that literally 100% of netflix content (based on around ~50 things I checked on) has between 3 and 4 stars.
This makes ratings completely useless.