That is definitely a problem with modern cards. It's not even collectors who caused it, but flippers. I can't tell you how many NBA players get cards as rookies and then never again. There's far too many.
One of my favorite things is to watch the new people entering my collection climb the charts tracking how many I have of each person. That's kind of been taken away, partly by the fact that I'm getting less new cards, partly because of the way current cards are made.
But I know anybody who primarily played before the 1990s, is not properly represented on cardboard. Somebody like Bill Russell or Wilt Chamberlain should be way higher than they are.
I know that in my top 10 most cards, every one of them entered the NBA between 1984-99, and the guy from 99 is only in the top 10 because he's my all time favorite and I chase his cards as singles. I know that anybody who entered the league in the 2000s is unlikely to make the top 10. LeBron is closest and he just cracked the top 100 in 2017, let alone top 10. The highest player who entered the NBA in 2007 or later, the year I took my break before coming back in 2012- the last I checked he ranked 367th. That was a few months ago and I've added a few of him since then, but he probably has not gotten much higher.
VERY slow trading due to health problems. Not transferrable so safe to trade with, just moving is painful and can't always access the cards.
Cardboard History My COMC
New Collection Website: Cardboard History Gallery (Still under construction)
Tips on how to make your scans look like the card does in hand (No more washed out, fuzzy scans!):