If you are writing HelloWorld-webscale daemon from scratch, then counting +lines is probably "ok", but considering some existing large project like Linux (for instance), you would be well off keeping people who has managed to retain functionality while removing lines. Old projects have a tendency to get a lot of old cruft in which tends to stick (chestertons fence and all that) but someone clever enough to rewrite and remove old useless code is a net win for you, so I agree that if you fire some percentage on most-committed-lines you either had a very recent project from scratch or the measurement is stupid.