When asked what value testers provide you often hear something like the following:

I’ll just hire good developers who don’t make mistakes.
Developers can test their own software anyways.

Here is my response to the question about what value testers provide.
Originally posted as a response to this post on LinkedIn by Bridesh about whether testers should be paid less than developers:

I like to think of testing as a force multiplier.

Maybe testing software isn’t as complex as developing it. But having someone focusing on testing the software allows developers to be more productive as well as produce higher quality work.

Allowing developers to focus on what they do best, product managers to focus on what they do best, designers to focus on what they do best, and operations to focus on what they do best — instead of having them all do something that is outside their expertise, causes context switching, and that they may be too close to see their mistakes — having someone who specializes is making sure things work, finding out how it doesn’t work, and informing all those other roles of ways they can improve their work in a disciplined (and diplomatic) way maybe doesn’t produce something tangible, but it increases the value and velocity of everyone else’s efforts.

Next time management questions what value testers bring, ask them what value managers deliver, and they will probably see the value of enabling others to be productive more clearly.