Your ARM smartphone and/or IOT device don't support UEFI or secureboot, yet they were still locked down and you couldn't flash third party OSes. The problem is locked bootloaders, not UEFI or secureboot. Fearmongering over a largely non-problematic implementation (secureboot explicitly allows you to load your own keys) is exactly OP's point.
>>gruez+(OP)
This sounds very much like "there are many ways to lock out users, why are you complaining about this specific method, when other platforms used a different one?"
>>jevote+t1
No it’s more like “why complain about a method that isn’t being used to lock down devices instead ones that are actually being used for that purpose”
>>jevote+t1
We should be complaining when it happens, not that any of these methods exist - they're super useful to have in many applications, eg. access control door locks, keeping PKI HSMs locked down, etc.