If you're small then I agree.

If you've got 100,000 concurrent users then this isn't going to work.

1,000,000 actions per minute means that all of the actions need a 99.9999% success rate to generate 1 error per minute.

Lots of 9's of reliability is hard.

Also. At that kind of scale you start observing lots of non-deterministic errors such as rare race conditions. As you drill into these rare race conditions you realise that they're affecting 0.001% of customers and you'd have to re-architect your system to eliminate them. You hit a point where it's not worth fixing those errors, so you build an error aggregating system to help ignore them.