Couldn't this work against any wifi? Impersonating a public access point gives you some extra unencrypted information so you know the server IP and can more eas

Couldn't this work against any wifi? Impersonating a public access point gives you some extra unencrypted information so you know the server IP and can more easily infer when a password is being entered, the same things you conceal by using a VPN over public wifi. But what stops a passive wifi observer who can guess those things or already knows them?