Personally I prefer knowing right away if a title is available or not from the search page instead of thinking I might be able to get it right away only to find out when I get into it that its not available. So yeah, I prefer to hide those under the advanced search instead of having a search result with hundreds of items of which only a dozen or so are actually consumable immediately. It was super annoying having to wade through tons of results which I couldn't even access anyways, and its not like requesting it would make it available in minutes.
Imagine searching a store front for some item like a shirt. You get thousands of results, practically every shirt ever made. In the old app, you have to step into each individual result to see if its actually for sale or not or you can click a button and maybe someday they might consider stocking it for you. Is this not a dead click?
Which one is more of a dead click, going into an item page expecting to access it but not being able to access it, or just not seeing it in the default view? In the end the result is the same, the user couldn't just hop into the book.
If dead clicks are to be avoided, the Libby is miles ahead of Overdrive. I've had many hundreds more dead clicks in Overdrive than I had in Libby, and I've used Libby way more than Overdrive.
Have you actually used these platforms? If not, are you really going to tell someone who actually uses these platforms every day what their experience is actually like while you've never used it?