Imagine yourself as a user of this service. You sign up, get the "email confirmation", think everything is good. A day later you notice that it isn't working, check up, actually read the email and click the link.
Now you want to report a bug. What do you say? How do you explain that you got it to work, but it could have worked better? When there's a large helpdesk, this kind of feedback is nearly impossible to give in any meaningful way. Even if you could speak to the coders concerned, often it's hard to get them to think in a different way and see the problem.
So it's obvious but it's hard.