In text boxes in some applications, enter submits the entered text, and ctrl-enter forces a newline (not at my computer, but I think Slack does this). In others, it's the other way around (pretty sure GitHub does this for comments). I don't know how we got here and I don't know how to fix it, but "bring back idiomatic design" doesn't help when we don't have enough idioms. I'm not even sure if those two behaviors are…
Infuriatingly, some apps try to be smart — only one line, return submits; more than one line, return is a new line, and command-return submits; but command-return on just one line beeps an error.
Years of muscle memory are useless, so now I’m reaching for the mouse when I need to be clear about my intent
So much is solved when developers just use the provided UI controls, so much well-studied and carefully implemented behavior comes for free