That's the point Kernowlock about crates, that dogs need to be crate trained, so their crate becomes a safe haven. If the crate is used to isolate the dog or to punish the dog, the dog will become anxious. I had a foster who'd broken out of 3 crates, chewed skirting boards etc anything she could get into. The dog had been left for 8 hours during the day, let out briefly in the evening, unless the owner was going out again in which case it was crated from about 7pm - 7 am.
Within two nights, the dog was sleeping through in her crate. She went in happily during the day if she wanted to sleep or rest. She needed a proper life, with regular routines and once they were in place she was a lovely calm responsive dog
My old rescue came aged 18 months or so, he was never crated. We had fosters and puppies as he got older. They were crate trained and he decided these crates were a Good Thing and would take himself off into one to avoid the rest of the dogs. It was very helpful when he became infirm, we could leave him happily with the crate door closed if we had to go out. This meant he could be quiet and also he couldn't fall on the wooden floors without me there to help him up.
I understand your comments BlueBelle, but I do believe crates can be used positively.