A lack? There's a huge and often price-insensitive market in decades-old manual-focus lenses for the Sony mirrorless cameras to the extent that I've given-up trying to find bargains and curiosities amongst 35mm lenses on eBay, and I've been in this hobby for nearly 30 years.
The only untouched seam of treasure appears to be medium-format lenses ( Mamiya, Hasselblad, Pentax etc ) which are too big and bulky for the mirrorless crowd.
I know there are tons of old lenses on the market. For me the main reason to go with Fuji was that they have a 100-400mm lens for which Sony doesn't have an equivalent. Obviously this may change but as of now I find the Sony APS-C lens selection a little uninspiring. I thought about the A7ii though but I didn't like the handling.
