Reading through all this makes it apparent some aren't being up front about the reasons to limit steel core use. It's about shooter safety, first and foremost. Richochets are a highly uncontrollable situation, no one wants a shooter hit, and the worst case situation is someone would be killed. In a competition with dozens of individuals watching within range, the odds go up.
Damage to the targets is obviously less than what is spoken about, but in the long run, hundreds of shooters over time will destroy a plate target. It will only increase the risk of ricochets.
"Safety First" is the main reason, and should be the first reason given. "Shot up targets" sounds like an excuse to avoid looking less than macho. I call BS on that. It's not about the targets, it's about shooter safety, which is far more important. Man up and say so. It's safety first.
Anyone who wants bullets flying back can find the nearest recruiter. On a range, it's a game, not life and death. Don't make it that way.