The semantics of this go beyond the use of "components" at Shopify.
Everyone knows that "modular" implies the thing can be taken out and used in a different context. That's basically verbatim from the dictionary definition. You don't need to be a software developer to know that.
And yet for years the word has been thrown around in discussions of Packwerk as if it's some weaker thing. It's not. Things that are not isolated are not modular. Anything less is something totally different.