My SO works in accounting, and they really do run without guardrails. And yes there are a ton of different software packages that people can buy for various uses (and do).

The main problem here is that Excel is so very flexible, and everything else is not (generalizing here, but it gets the point across). So the after the third time you are using Excel to handle the exceptional cases, you start to wonder why you are not using it everywhere else.

Of course the counter-problem is that it is so flexible that it accommodates your mistakes without pointing them out.