Your experience is selection bias. And if you never had issues with ext3fs, I assure you it's because you never checked.
The context was the sweeping generalisation that Linux devs and that they don't care about regressions, see up thread by @imiric. In that context I've not had regressions. More explicitly, for this narrower context, I've not had regression bugs in ext3/ext4.
I'm not making a claim that I've not had never had ANY issues or never have to fsck my drives; nor am I making claims that nothing has ever appeared in 'lost+found', nor am I claiming that ext3/ext4 are perfect. Nor that Linux is perfect.
Just claiming that the software quality in the Linux ecosystem is very high. I'd say better than many closed-source solutions -- which couldn't be proved anyway.
I've only been at this since 1994 and still have a lot to learn. However, I don't learn much from the "you're wrong and not good" type of conversation.
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.