I think a lot of people don't. The word 'cis' seems to have been invented because some people object to the term biologically-female or biologically-male, but that's generally what it means.
To add, cisgender is not that new of a word, it's been around since the 90s in English.
Using the term "biological male/female" is an immidate red flag as it carries with it the insinuation that trans identities are not ligitimate; you could just say "not trans." Hence the heavy use by right wingers and bigots.
Specifically transphobes prefer saying biological this and that rather than use a trans persons gender identity as a way to purposefully invalidate them