On top of that, our security standards have also gotten higher. No one was worried about corrupt spreadsheets causing segfaults in 1995. But today that corrupt

On top of that, our security standards have also gotten higher. No one was worried about corrupt spreadsheets causing segfaults in 1995. But today that corrupt spreadsheet is just as likely to be a malicious file from some attacker on the internet, deliberately crafted to exploit the buffer overrun behind that segfault. Any piece of software that might conceivably touch attacker-controlled input needs to be hardened against this sort of thing. We're also going to be seeing more and more pressure to make things multithreaded. So so much of the old software was designed back when concurrency just wasn't in the picture. That's why PID reuse races are so nasty in child process management. And why anything that touches the environment (which lots of standard libc functions do under the covers: https://rustsec.org/advisories/RUSTSEC-2020-0159 https://rustsec.org/advisories/RUSTSEC-2020-0159) is unsound in multithreaded programs. Making everything threadsafe is genuinely hard.