Why Do So Many Programmers Hate Agile?

Here is an article about this topic.

The key point of Agile is multiple iterations and between iterations getting the feedback from the customer to make sure the features of the application can cover the customers' requirement. Think about Waterfall, it is collecting requirement fist, then design, coding, testing, then delivering the application to customers. If there is any mistake in requirement or the customers change their mind after the requirement collecting, the gap cannot be found or cannot be passed to developers. Agile is to involve Customer review as early as possible.

But I saw a lot of projects using Agile just as a tool to measure the output or productivity of the developers. This is not correct and I won't like this kind of Agile as well.