C++ Lambdas are capturing, so they aren't plain old functions. They evaluate to closures: function + environment. In C++ the captured environment is explicitly written in the [] section of the lambda.

The issue that I think the top comment is alluding to is that lambdas cannot capture by reference and then return, due to that stack frame becoming invalidated, which is a fairly large limitation that prevents swaths of lambda heavy code from working.

I personally think that this is a fine tradeoff for what C++ is: there's still plenty of utility in lambdas for simple higher order functions like maps and filters.