They have worded things dishonestly to make you think that POP can be replaced by IMAP. The IMAP support is only available in the mobile app (not gmail.com) and

They have worded things dishonestly to make you think that POP can be replaced by IMAP. The IMAP support is only available in the mobile app (not gmail.com) and isn't a "fetch" that integrates fetched emails to your Gmail inbox. It's kept as a separate inbox.