I find it implausible that this can catch all the ways that C programmers actually do mess up (as one for ~40Y). I can make even languages such as Java leak me

I find it implausible that this can catch all the ways that C programmers actually do mess up (as one for ~40Y). I can make even languages such as Java leak memory even though it shouldn't be possible, nominally, so just knowing that something is returning heap-allocated memory somehow doesn't seem to help much. But I have only skimmed the page, so hopefully I am wrong!