I would hope this would be a common courtesy toward people, but it isn't as common as it needs to be.
There are a million reasons why someone may not want to go through with an appointment. However, it isn't okay for you to arrange time with them and then ghost the individual. A quick message saying "no longer interested" would suffice with no more explanation offered.
It is disrespectful to have someone hold that time only for you to ghost them. Please be respectful of everyone's time on here and just communicate.