Jim,
I don't have any numbers, but did find this.
[size=78%]https://golfsupport.com/blog/sports-related-injuries-golf-more-dangerous-than-rugby/[/size]According to that, there are 40K ball strikes a year out of about 434 Million rounds or about 1 per every 11,000 rounds.
I actually think Doug Siebert's first pp is just another attempt to fit nearly any subject into a long standing anti-USGA narrative prevalent here and in many places. I doubt many could find stats to truly back up the correlations made.
I doubt equipment really raises the amount of ball strikes. First, the number of 300 yard drives, much less 400 yard drives is so small in non tour golfers, its not significant. Second, a ball and person being in the exact same place at a precise moment is also pretty low statistically. Why would .001% of longer drives necessarily put another golfer in that area rather that a shorter one? It would seem some relationships between holes might change, but too few to mention.
Also, statistically, contrary to popular belief, longer hitters are also straighter. For any given swing speed, there is only so much ball energy. Its hard to hit a ball long and wide - If it uses 92% moving forward (mean) only 8% is moving sideways, etc.
Average golfers, who make up 90% of golfers on most courses, aren't hitting it either further or straighter for the most part. As JK says, some tech is aimed at straightening out shots, most is aimed at distance, but perimeter weighting may help a bit.
I actually put this question to Frank Thomas years ago in his then regular Golf Magazine column. He said that new clubs won't make existing condo canyons any safer, but shouldn't make them worse either.