It's a hard piece of advice to make use of. I couldn't say whether I assume everyone is like me or not: it really depends on what we're talking about.
Are you okay with sharing what it was about concretely? That may be more of a takeaway, to learn in which way people aren't all alike, than the general statement that not everyone's the same
It was in response to some UX considerations for a feature I wanted to patch into vim. I must have had a bad week, I was needlessly combative after an initially abrasive response from another contributor who closed my issue without consideration. Bram stepped in and finally got the conversation moving.
We couldn't come to an agreement on how to implement it in the most robust way... meanwhile over at neovim a PR was submitted and merged, and a backwards-compatible solution provided within 3 days of me filing an issue. :-)
Are you okay with sharing what it was about concretely? That may be more of a takeaway, to learn in which way people aren't all alike, than the general statement that not everyone's the same