Surely, important bugs are ones that make it into production and impact your service - so any solution that catches bugs and stop them making it into production aren't catching the important ones.

Your point about automated testing only catching known knowns and known unknowns needs to be understood by everyone in the IT industry, because that's why it's so powerful - it frees up resources that would otherwise have to be looking for those issues, which can then spend their time looking for the unknown unknowns.