I think you are under the misperception the 1952 Topps Mickey Mantle could be easily acquired by the few mail order firms of the time.
In about 1969, I wrote to Bruce Yeko at Wholesale Cards Co. inquiring about the availability and price of that prized piece. Writing me back in his jagged scrawl, he had written $15, but crossed it out and wrote $20, and the cautionary "when available".
I am certain nearly ever '52 Mantle to be had were part of complete sets they had available. The price for them at the time seemed astronomical; today of course it is minuscule. Having to purchase the entire '52 set just to get the Mantle, or at least the primary motivation, would have been a substantial deterrent to any kid, tween, or teen. Of course, as we all know, in retrospect .....
I was able to finally get my 1952 Topps Mickey Mantle from Larry Fritsch during the first couple weeks of 1973. Oh how I miss that glorious card........
Yeah, I know, it would be worth a small fortune, but I miss the card; it's such a beautiful card of Mickey.
Nice trip down memory lane, sort of. ---Brian Powell