Analytics has transformed basketball as much as any sport. Arguing that the teams were better 20 years ago is arguing with math. Or 75% of the teams in the country are stupid and should throw analytics out the window. Is Jay Wright stupid?
Also, and this is also inarguable, the depth of talent today is light years ahead of where it was 20 and especially 30 years ago. 30 years ago, a kid would play his 20 game high school season (often with a random teacher as a coach), a few camps, and the top players would do AAU tournaments in high school. Youth basketball was usually just town leagues, with a few travel leagues scattered around that might play 10-15 games a season. A lot of the players developed completely on their own. Magic Johnson talks about learning to dribble by bouncing a basketball to and from school, and Reggie Miller said his shot is so weird because it was hard to get a normal shot off against his sister playing 1-on-1 in the driveway. Cool stories, but not a scalable infrastructure for developing lots of high level talent.
Today, most D1 caliber players start AAU in 5th or 6th grade in addition to town travel, and play about 50-60 games a year of competitive basketball. By the time they reach high school, they have probably played over 200 games and had 300-400 practices with coaches that are better on average than the high school coaches were from the prior generation. In high school, they are probably playing 50 offseason games a year plus camps.
The top players are still the top players, but the depth of talent today is just better. Unless you want to argue that more practice and more games makes a player worse at basketball.