I agree with this. It irritates me hugely when we estimate tasks by complexity and then use our estimations to determine which tasks we can accomplish in a sprint.
Exactly - and it also ends up seeping back into the estimation as a result, 'a junior/recent hire/someone unfamiliar might pick this up, so let's make it [the higher number discussed] to account for that'. If it was actually complexity, it's just as complex whoever works on it. How hard they find it and how long they take might vary, sure, (and that's fine, and sometimes it'd be me taking longer than someone else) but not the work's complexity.