You’d still be able to change passwords via phpMyAdmin if they are salted, it’s just trickier. Man, I’ve had to hack into sooo many sites for clients that forgot them or developers who disappeared or whatever, e.g. http://tipsfor.us/2009/10/25/forgot-your-modx-password-you-can-reset-it/
If you have FTP access to a site, you could retrieve the salt, typically you’d just add it to your password, e.g. if your salt is ’1234abcd’, and you wanted to change your password to ’p@$$w0rd’, you’d actually store ’1234abcdp@$$w0rd’ in the database and hash that via MD5 or whatever algorithm is used. Or, you could also change the salt entirely, e.g. to a an empty string. Or, you could update the admin password in the database and then request a password reset. There are lots of ways to open backdoors.