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.