Something I noticed personally being a US 11.5 size for most of Etnies cupsoles is that shops are hard pressed to stock more than 1-2 units of sizes 10 - 13 (especially the half sizes like my 11.5). My local shops that do carry Soletech are slim or none for 11.5s. I regularly come in looking for 11.5s so they get the hint that they should stock that size more in their pre-books since I prefer to buy there 90% of the time.
Either those less common sizes for them don't sell as well so they don't stock them or they don't stock them as well because they don't expect them to sell as well. I get why they don't chance it if they're not sure if it will sit or not.
For etnies mostly, and to a lesser degree emerica and es, I've had to buy directly from their site OR scour for random shops & stores online for a color/model I wanted.
Soletech is perhaps, indirectly undercutting the very skate shops/scene/brand reputation they want to portray/support in order to stay afloat by nudging people to go D2C. We see the same practice with big brands having high minimums for pre books in shops, so they push us to buy directly with good sales/artificial scarcity, etc.
I can't offer a solution here, but thought I'd share that thought and see if anyone else has observed it. Maybe restructuring the pipeline of brand to consumer for buying their products needs adjustment alongside the quality and image of their footwear.