Tons of papers are published every year for the sake of publication, careers, .... absolutely not for the sake of science. Most of them do not even contain any significant delta with previous research.

An important activity of the researcher is to sort between interesting papers and garbage, since the selection process of even high level conference is deeply broken.

Just read SIGIR proceedings where every paper beats the previous baseline by 0.X % on datasets that do not represent the real problem, it's just an example among many others.

Also check this interesting analysis where the authors analyse best vs top cited papers over a span of ten years: http://arnetminer.org/conferencebestpapers

Here you can see that some conferences where able to identify lasting value and others not.