We ran under valgrind and multiple sanitizers (and continuously ran those with high coverage unit and integration tests). We ran fuzzers. We had strictly enforced style guides.
We still shipped multiple use after frees and ub-tripping behavior. I also saw multiple issues in other major libraries that we were building from source so it can't be pointed at as just incompetency on my team.
Basically, it might be possible but I think it's exceptionally more difficult to write memory safe C++ than this thread is making it sound.
Everything "is possible" in the sense that in theory you can do it. But if time and time again people fail to do it. Even people who invest almost heroic levels of effort (see above: valgrind, multiple sanitizers, and so on) you get to the point where you have to accept that what is possible in theory doesn't work in practice.
The "strictly enforced style guides" strictly enforce '90s coding habits.
