This is very unprofessional but not uncommon at bigger companies. They just don't care. First, chances are you were not even interviewing for a real position, they were just using you to collect data ("who is out there", "what kind of money do they want", "what are they making now", etc)
Second, why take a chance to get back to you and tell you it wouldn't work out? You're gonna ask why and what are the gonna say? "Not a good fit"? Even this made up reason doesn't work anymore, since people start suing for discrimination.
I've found that this behavior is very rare at small shops and startups since they care about their reputation and try to not alienate people in their area.
Startups tend to work faster and schedule things pretty quickly. I found that the bigger companies are really good at putting people in a limbo and not bothering that much unless they really want you or if you were referred by someone at the company.
Second, why take a chance to get back to you and tell you it wouldn't work out? You're gonna ask why and what are the gonna say? "Not a good fit"? Even this made up reason doesn't work anymore, since people start suing for discrimination.
I've found that this behavior is very rare at small shops and startups since they care about their reputation and try to not alienate people in their area.