Until fairly recently, crates were virtually unknown, exept for in the show dog world.
This is because previously, no one got a puppy if they were out all day. Now people who are gone 9 or so hours a day still want puppies.
Crates can certainly be handy tools in the housebreaking process, but crates are being used in abusive ways now, with dogs spending more time in them than out of them, resulting in many dogs with behavior problems stemming from the isolation and confinement.
To me, leaving a dog or puppy in a crate all day is unacceptable and inhumane. If you have no time for a puppy, don't get one.