calling the entire fediverse "mastodon" is good because it normalises one particular platform above all others and makes users of other software feel like they're abnormal and not part of the main platform
calling fedi "this site" is good because it confuses new users and helps spread the idea that the fediverse is mastodon and mastodon is a single website and that website is mastodon.social
imagine how obnoxious it would be if people said "just bing it" or "duckduckgo it" instead of "google it". google has become ingrained in our language and i am NOT happy about it