alt Hacker NewsDev/shm is used to materialize them, and then you have the ability to isolate the downstream code you might use from accessing it by dropping permissions or sandboxing it away from a file. You cannot really hide your environment from anything in process, since it's such a low level construct.
Thus it's easier to leak environment unintentionally, leaking file contents takes effort.
Not at all clear why this is a better setup than a launcher shim that pulls secrets from a secret store and injects them into the environment as the program launches --- which is a pretty normal shape for these things to take.
I guess you could be thinking "subprocess inheritance" as a downside? But subprocesses often need secrets, and if you arrange for that with the filesystem you have the same problem. And, of course, files leak all the time.
More to the point, though: none of this has anything to do with whether you should add secrets to your .bashrc or whatever, which is the argument I'm seeing on the thread.