Of course Joe Armstrong could explain what I meant, but in a much better way: https://erlang.org/pipermail/erlang-questions/2003-March/007... (edit: see the "Why was error handling designed like this?" part for reference)
My personal interpretation is that systems must be able to handle crashing processes gracefully. There is no benefit in letting processes crash just for the sake of it.
Saying "let it crash is a tagline that actually means something else because the BEAM is supposed to be used in this particular way" sounds slightly "cargo-cultish", to the point where we have to challenge the meaning of the actual word to make sense of it.
Joe Armstrong's e-mail, on the other hand, says (and I paraphrase): "the BEAM was designed from the ground up to help developers avoid the creation of ad-hoc protocols for process communication, and the OTP takes that into consideration already. Make sure your system, not your process, is resilient, and literally let processes crash." Boom. There is no gotcha there. Also, there is the added benefit that developers for other platforms now understand that the rationale is justified by the way BEAM/OTP were designed and may not be applicable to their own platforms.
I agree on the importance of defining terms, and I think the important thing here is that "process" in Joe's parlance is not an OS level process, it is one of a fleet of processes running inside the BEAM VM. And the "system" in this case is the supervisory system around it, which itself consists of individual processes.
I'm critiquing a common misunderstanding of the phrase "Let it crash", whereby effectively no local error handling is performed. This leads to worse user experiences and worse outcomes in general. I understand that you're offering critique, but it again sounds like you're critiquing a reductive element (the headline itself).