Back in the day Mongoose had a bit on their webiste about supporting the brick and mortar (generic term, not the free pdf scheme), can't find it any more. ANd the lack of a proper distribution run speaks volumes.
Even if the Mongoose crew would hand deliver the books to the FLGS "through wind, rain and shrapnel hail" I would still be forced to buy Amazon. The next FLGS ist 80km these days and that is a WhitePoodle/Das Spielen Andere shop that carries NO SciFi. And no, I am not living in the middle of nowhere. Capital city (> 230.000 inhabitants) in a densly settled area of germany
The B&M shops are dying by the dozend for various reasons (My other hobby, Scale Modeling has similar problems). Those that survive are "game shops" with a (very) small RPG corner. And those do not stock Traveller/CP2020/RIFTS or other "small" game systems since they have low turnovers and consume space.
Most shops are also badly located/have no parking space/lousy bus reachability and most of the time the guy in there is "bored teenager to stupid to get a better paying job" and not a hobbist (At least THAT ist better in ScaleModeling) Add in opening hours not suited for people with a regular 9-17 job (And those are the ones with the money) and the spiral gets faster by the second.
Now enter Amazon and/or DTRPG and Kindle/PDF versions. I can buy the book "just in time" and have it within minutes, it is cheaper and the preview often is "as good as" what I can get in many shops these days (Gone are the shops with ample space to browse a book in detail).
Possibly more important in D since at least the printed 13Mann translations are fixed price due to german laws (Buchpreisbindung) but each version (Softcover, Hardcover, EBook etc) can have a different price.
Add in that with books ordered by the Internet I have a "two weeks return and money back, no questions asked" option in germany (Fernabsatzgesetz) while buying a book in a store is a "take it, money is spend" situation (In germany the customer is king and the shop owner is Rob S. Pierre)