So then why do I have the ability to stage individual lines of changes, creating commits that do not reflect a state that my system ever had, ergo was never tes

So then why do I have the ability to stage individual lines of changes, creating commits that do not reflect a state that my system ever had, ergo was never tested or compiled in, thus can not be known to be working? Also, what if I use a remote to synchronize between different machines I work on on the same code base?