Now hold on... you're saying two different things here
The historical data on steam reviews is good, because it just requires more filtering options. Right now its a big heap of chatter of which the vast majority of extremely low quality... although I somehow doubt that historical data will make quality go up. 10 year olds will be 10 year olds and stupid doesn't suddenly become smart.
But good games getting tanked forever because premature launch... that is really another one of Steam's big failures, the whole Early Access thing and the incredibly lacking quality control on that.