My best guess is that the password-sharing crackdown is a response to slowed subscriber growth in an attempt to keep that growth at some astronomically high tar

My best guess is that the password-sharing crackdown is a response to slowed subscriber growth in an attempt to keep that growth at some astronomically high target. "Got rid of the best parts of their catalog" is definitely a subjective take. I'm going to assume you're referring to much of their licensed content which is a hard-to-scale problem unless you continue to throw money at it. One of Netflix's problems is that the profits it takes today doesn't get realized into "good content" until a much later date when production is wrapped and released.