Tennis is the only sport that does this. Baseball has been played since the 1800s & Babe Ruth regularly tops all polls of past greats, current players, fans etc as who the best player of alltime was & he played primarily in the 20s. Imagine if they decided on 1978 as the starting point for historical discussions, it would be a joke.
Tennis has a unstable element, namely the racquet issue. Had baseball switched to aluminum with ever progressive metal technologies, most of the records would be meaningless. Even now with the steroid issue, many are arguing how to contextualize the 90s hitting stats within the proper context.