What Brianne refers to in the video is business-to-business communication, in which you (rightly) don’t want to crimp the impression you make on an audience by saying “Web Comic” in your title and then “webcomics” throughout your text. Audiences’ degrees of testiness about this kind of varies, but the question of course is do you want to leave that door open? or how far are you willing to leave that door open? Because you know that some people will just focus on that stuff and not get your message.
Style guides in general exist wherever a publishing company or bureaucracy (and most bureaucracies publish) wants to give its writers guidelines to hew to in matters such as what titles should be made italic, set within quotation marks, or just capitalized. For instance, the US government has its GPO style Guide:
https://www.govinfo.gov/features/new-edition-gpo-style-manual
And NASA has theirs:
https://history.nasa.gov/styleguide.html
Note that NASA states that certain parts of its style accord with the Chicago Manual of Style, which is the 800-pound helpful gorilla for writers in many genres (noting of course that many disciplines have their own unique style guidelines for publication).
Style stuff is boring, tedious, infuriating when you realize you can’t see your text anymore after reading it 20 times; but don’t be this person:
