Why would anyone do that? People talk and people remember. Additionally, you never know where something might lead. My own company, for example, is work-shopping this new play (the one we're casting for), we have two movies going into production, we are working on a TV series, and we are planning a theatre season for 2019. As petty as this sounds, I will remember every single person who failed to show up, didn't call or email to cancel. Sad to say, I'll probably remember them more than the people who actually showed up, gave me their all for 3 minutes and didn't get the part.
Guess who I ended up casting? The guy who rescheduled. Why? First, he killed the audition. Second, I knew he was professional and would probably treat the role and the play with respect.
The business part of being an actor is hard. Really hard. It is as difficult, if not more so, than any other career. If you called a plumber and he never showed up after confirming a time to fix your sink, would you ever call him again? If you missed half a day of work for the cable guy to show up in that asinine four hour window and he never called but just didn't show up at all (okay, maybe a bad example), you would, at the very least, be somewhat annoyed. Do yourself a favor and treat your creative career like a profession not hobby. If you truly love what you do, afford it the people in the position of getting you work the same respect you would any other professional. Don't make me have to write something like this again.
Thank you. Next!