I don't think we should set our expectations based on an extreme outlier. qmail is special, and we can't expect most software to get to its level of security/safety.

Put another way: if you have to rely on programmer skill or attention to detail in order to guarantee something, that will always be a losing bet, on average. The existence of a tiny percentage of programmers that can clear that high bar does not make it a valid strategy.

It had one bad cve it seems, but that's exactly what I mean. It only takes one mistake, of course you can learn and never make those mistakes again, however, that is an unrealistic expectation in software that receives hundreds of feature updates a year especially when it comes to core applications as basic as communication when it wants to support image previews, reels and whatnot.