It's not a reach actually NBA player themselves have come out and said that it was more difficult. These are primary sources, not speculation online.
Kobe's efficiency numbers pale in comparison to Jordan or Bron.
Kobe is the all time leader in missed shots by nearly 1000, he had to increase the volume substantially to be able to maintain the same output.
Kobe and Bron both came out of high school, so their playing field is even in terms of possible years. LeBron has a very large % chance at passing Kareem for most points all time. Why couldn't Kobe do this if his midrange style was so effective and he had the ball in his hands so frequently?
The second part proves my point. You can't say Jordan was definitively a better off ball defender(which you did) when he never had to defend against the kind of secondary and tertiary rotations that are used today.
Pick and roll play was much less advanced, more time throwing the ball in the paint and watching the C work. Not having to chase guys around multiple screens. All of this factors into modern defense, not just defending ISO situations.