Without necessarily agreeing entirely, let's look at something that changed in the past 20 years.... the rise of the Internet.
Could anyone here disagree that many people seem far more inclined to be rude and callous to others amid the anonymity of the Internet, than is normally the case in FTF RL? Well, if you've been on DP long you'd have a hard time disagreeing.... and DP is moderated more strictly than most internet forums! Yet we still see a lot more rudeness, if not downright hatefulness, than you normally see in FTF interactions between adults.
Reason? You can be rude, crude, lewd, mean, petty, spiteful and hateful on the Internet.... and generally be insulated from your victim's immediate reaction. They can't punch you through the computer screen. If they even know who you really are, they can't get at you until much later after the initial fury and indignation has perhaps worn off or cooled down... and I think that makes a huge difference.
Another reason I think those who primarily socialize on the internet are often less empathetic than they would be IRL FTF, is because they don't directly and personally SEE their victim's emotional response, the hurt and pain on their face, that they would in person.
And over time perhaps some of these folks become more insensitive in general, enough so to carry their online behavior into the RW.
Now we've got a generation of children reaching adulthood who grew up with the Internet....
Makes you wonder, anyway.