I think you’re missing the point. Unless you were actually measuring the content of your file system with a reasonable quality hash function, you likely had actual data corruption that Fsck will never see. Fsck can’t check data on ext*.

Unless you were routinely running mtree or something similar, you’d honestly have no idea.

My point here is that software can appear to be fine when it’s actually shit because most people won’t notice any kind of corner case. All you’re saying is that you’ve very likely missed the corner cases.