I think some of it is analytics, I think some of it is specialization too early. Like Nolan Ryan probably threw a baseball every day as kid. But, he likely only had the one baseball season as kid. Where now days kids, have baseball season all year long, then high school, then college, minors. I think arms just get blown out.
So I do feel there is more wear and tear on arms even though it seems like guys pitched way longer, etc in the 60s, 70s, 80s, and 90s. I think the influx of analytics doesn't hurt though. Like x guy is not good the third time through the lineup. So that can impact outings. Pitch counts on young arms also plays a role.