One common reason to delay a first date is due to an attempt to learn more about the other person. I found the first few minutes of the first date are worth more than dozens of emails.Another reason to delay would be if the person you are communicating with has expressed extreme reservations about meeting people from the internet.
After the hour was over, I explained that I only extend the good dates and since ours was a great date asked if she would be up for miniature golf (she was).
Other times, people are just reluctant to meet you because they are still trying to decide if they like you.
After a while, any of these cases is a waste of your time.
In contrast, many times the dates ended with coffee or lunch.
This approach is a cousin to the having-your-friend-call-you-and-faking-an-emergency act that some people think is so slick.