Overly Strict KYC/AML: Is It Really Good?

Lately, I've noticed many brokers (especially those trading $BTC or other cryptos) are getting annoyingly strict with KYC/AML. Sometimes, just to deposit a small amount, you have to submit piles of documents and verify your identity for days. Not to mention the source of funds, which sometimes requires such detailed explanations that it feels like we're criminals. I understand it's necessary, but sometimes it's too much and feels like a waste of time.

Has anyone here ever missed a trade due to document issues or had to switch brokers because of these petty things? And what level do you think is just right, not too much, not too little?