I'm not an OEM but I'll hazard a guess: long term hardware support assures that field replacements will match the exact specifications your are expecting. Large scale implementations have historically relied on a reference device to make sure you don't have a thousand different profiles running around.
Combine this with a JIT supply chain, and nobody making phones is going to want to stockpile a bunch of old Qualcomm chips they aren't sure they'll ever need.
Combine this with a JIT supply chain, and nobody making phones is going to want to stockpile a bunch of old Qualcomm chips they aren't sure they'll ever need.