It's called having some common courtesy. Companies such as yours that think it's beneath them to spend the 10 seconds to respond back to people is a huge redflag that they're filled with arrogant pricks.
Unfortunately this courtesy is anything but common in my experience, it's not the exception. Hell, I've had companies and recruiters disappear after showing initial interest, e.g. after the phone screening stage. Call me a cynic but these days I'm pleasantly surprised when I receive even a negative reply.