When lambdas first came about there was a lot of "meh, I could already write a functor just fine" but the ease of using them is just so much nicer and the readability of the code is so much greater. Just writing a plain for loop would often be less code than using an STL algorithm and a custom functor so there was very little incentive to use the highly tuned STL algorithms if it was just going to take more boilerplate. Now there is and we are finally seeing C++ programmers catching up to the insights that functional programmers had made a long time ago
Others have said this but comparing lambdas to iterators is a very odd decision because they are completely unrelated things.
The conclusion should really be that anonymous functions aren't as intuitive as "regular" imperative code. The regular code walks you through what is going on in babysteps so even a new user can figure out what is going on. The way with lambdas requires a bit more knowledge but for working programmers who aren't learning C++ for the first time they are obviously a big boon. Sometimes you have to learn something slightly more complex to reap the benefits of it. Pointers are very hard for brand new programmers to wrap their heads around but nobody would argue that judicious use of them can be a real benefit (or essential, even) in some situations. This is like concluding that smart pointers are bad because they are less explicit about what is going on. You still need to learn C++ manual memory management but your code will clearly benefit (both in terms of verbosity and memory safety) by using smart pointers 95% of the time.
1. CppCon 2016: Ben Deane "std::accumulate: Exploring an Algorithmic Empire" https://www.youtube.com/watch?v=B6twozNPUoA (std::accumulate, fold essentially, has been in C++'s STL since the beginning and Stepanov probably had it in mind before C++ even existed but we are just now getting lectures like this and I think lambdas are to thank for this)