>>5023798
Let me give you a rundown:
>A) You raise them from a pup to associate their bed or toys with the crate
>B) You don't try to crate train a dog that you haven't climatized to associate their crate with their bed or toys
>C) You don't need to close the crate when absent unless it's an absolute emergency such as >>5023799 stated
>D) If you have an anxious dog they can benefit having a hide to retreat too which a crate can provide (pretty common with sighthounds)
>E) You ensure the crate is big enough for the dog and has acess to water and as stated before toys
>F) Once crate trained it makes it far easier to transport your dog in the future
>G) Dogs don't have the same human conceptions of crates as we do, so arguing crate bad cuz it looks bad is not really an arguement

If you follow that then crate training is fine. If you don't it becomes a problem.