[something123]

I guess it's a matter of opinion but I think you're wrong that you have to redesign stuff. Most of the guarantees in essence already exist b/c of best-practices (like RIIA) - they're just not guaranteed by a validating program.

Don't diminish it, b/c the presented solution is non obvious/trivial. If it was, it would have been done ages ago.

So either A - The Mozilla folks may have not thought of this solution

B - At the time of Rust's development C++ was stagnant and not evolving as it is right now. There wasn't a lot of hope for fixing it at the time. It's thanks to the work of several people that the C++ standards committee now is a fast moving organization.

If Mozilla were considering starting the Rust project in 2016 I don't think they would have gone ahead with it