Platforms like YouTube and Spotify are trying to make podcasting a closed medium, which goes against its roots as an open platform for audio shows. They leave out import and export options as well as the ability to listen to externally-hosted podcasts or password-protected feeds, which comes standard in just about every other podcast player. Their reasoning for doing this is simplicity and to watch or listen to all your media content in one place, but the real reason is it's easier to track your every move and target more advertising to you.
