That's not moving the goalpost, that's keeping the goalpost on the original topic. "Is steam making online predation worse by not having two separate storefronts" - Answer: Clearly, no, since there are multiple storefronts and that has nothing to do with how children are exploited online.

But if you want to talk about the rarity of predators (I'm taking the numbers in the article here): 1500 reported cases / year of sextortion in the US and nation partners is pretty damn rare. Even assuming non-reporting rates are 500x the value given in that article, that's still 750,000 victims among ~1,000,000,000 people, or a 0.00075% victim rate. You're only twice as likely to have been victimized per year as you are to have been struck by lightning. I don't... like, I don't know what else to call that but rare.

(The above numbers are just about sextortion, a very broad category of crime and that which is the crime in question here. Broadly, "pressuring kids online to send naked photos of themselves". This number doesn't include physical abuse crimes, I did confirm that in their sources.)