Thinking that it's a device specific passphrase and not an essential part of the seed
Discussion
Not sure what you mean.....a passphrase is not device specific and is not part of the seed but added to the seed. Any passphrase added to the seed makes a new wallet.
Re-read the original post - the Bitcoin mantra is that you only need your 12/24 words
The OP was about the pitfalls with added complexity in a setup, passphrases specifically.
I am saying it is maybe more correct to educate people on the importance of testing/proving recovery and good backup practices, and to not blame lost funds on something other than common user sloppiness.
I didn't get that from your replies, but you're right everyone should test restoration