This seems like a strange comparison to reject. Baseball cards were originally 'prizes' packaged with other products, and they were randomized to create excitement and keep people brand-loyal while they hoped to find the prize they wanted. They're the precursor to CCG booster packs, and from there to MMO loot systems, so of course we should compare loot boxes to baseball cards!
And it's even darker than that. The major originators of baseball cards were tobacco companies, so you'd go out and buy ATC cigarettes in hopes of getting Honus Wagner. The causal chain from baseball cards to smoking to cancer was far tighter than the chain from loot boxes to problem gambling to suicide, and yet we're told that loot boxes are a real problem, not like baseball cards. Exploiting people, and targeting kids, with randomized prizes is way older than B.F. Skinner's work.
It's a minor side note of course, not the core of the discussion, but it's a bit concerning to see a researcher specializing in loot boxes botch his history so badly.