It's most likely a lot more complex that these hot-takes at least.
It's most likely a combination of a lot of different factors, not least being better shooters and more skilled (as is the case in every sport, except that old head basketball fans like to act like basketball is the only sport where this development isn't possible. Like we had centers moving like PGs before. Or dudes dropping 3s like free throws or balls stuck to their hands like it was glue to them pause).
One could perhaps also check what the Europeans say about the Euro leagues.
Over there it seems like the energy management over a season isn't as timely planned as in the NBA, therefore the players defend, move and run like there's no tomorrow. The fans are wilder too, giving more distractions. But of course, you've got to combine that with the fact that they aren't nearly as skilled.
And then again, there's countless of other reasons like rules and soft refs, or formations not including pure defenders with one focus.
Another thing one has to analyze was the ppg drop from the 70s and 80s to the 90s.
But it seems like as if, with all these various reasons, the old heads will never attribute it partly to skills.
It's a lot more complex, that these twitter one lines cats be dropping.