Is it though? With this technique you would just need to grep a password dump for permutations of the service name. For the ones you find there is a good chance

Is it though? With this technique you would just need to grep a password dump for permutations of the service name. For the ones you find there is a good chance that the scheme is used on other sites. So now you can try the big sites with a high probability that the login works. With password re-use you would need to guess if they re-use it. With this you know.