Our paying customers don't appreciate bugs. A layer of testing _is_ fail fast/early because it prevents an issue before it gets to the customer.
One gig I had: several times per week the site would go down and nobody could log in. People were just pushing code and yolo'ing into prod. Paying customers were churning. The solution? A single cypress test on a canary node that logged in and edited one setting. 2 or 3 minutes of barrier to production and now the site doesn't go down periodically with deploys.
I am not saying you should not test. To me it seems obvious that you test what you create. But it is impossible to test everything.
When you fail fast you are quicker to notice it yourself. And when it was deployed without you nothing the bug it will still surface very early because it breaks your app.
One gig I had: several times per week the site would go down and nobody could log in. People were just pushing code and yolo'ing into prod. Paying customers were churning. The solution? A single cypress test on a canary node that logged in and edited one setting. 2 or 3 minutes of barrier to production and now the site doesn't go down periodically with deploys.