I know a few folks that love these things. I've never quite understood it......... I feel like it is artificial rarity. It's interesting though. Kinda like the lowball sets or VAMS, or 1945P FSB 10C, never understood those either. The whole hobby is about coins, not outdated plastic or a tiny die crack or detail you have to see squinting at it even under a loupe. And a doiley? Yeah it's neat. It's a fancy paper label. But $4.5K+ neat? Id rather collect stamps. Lol. That's my motto.
I voted for Over rated. Not into collecting slabs. @ddddd, I do respect your opinion about owning these old holders as a way to track grading history. Interesting perspective. I never thought of it that way.
Whether or not someone wants to be interested in older slabs which are part of numismatic history and no different than collecting Coke memorabilia is their personal choice. That said it isn't debatable whether or not they are the real deal when it comes to having premiums and collecting interest, the market has shown that over and over again that they do. The Doily is one of the best for sure but the first two rattler versions were each only used for a couple days when they first opened and are rarer with bigger premiums than the Doily last I checked.
That is what people tend to misunderstand, it is NOT collecting coins by the rarity of their slabs, it is collecting rare slabs that happen to contain coins. I only know of one person who collected coins based on their slab and that was because he wanted examples of all the NGC holders but wanted each to have a 1903 O Morgan dollar in it. It is the SLAB that is the collectible here, not the coin. I collect coins, and I will not buy slabbed coins. I also collect varieties of slab, and in those cases I do not care what the coin is in the slab. The slab is what is important. They are two different (but related) fields.