Have been using scrum/agile for over a decade now. To most of the companies if not all I worked for, agile/scrum was nothing but just a fancy buzz word to the management team. They just did what they were already doing under the name of agile.

Put all that aside, scrum/agile is actually pretty good on tracking small and simple tasks. So if the whole project can be broken down to nice and small tasks and the estimates were accurate, agile/scrum will work perfectly. Unfortunately all the project I've ever involved were complicated, some were even super large. We humans are pretty bad at estimating and no surprise most estimations were way off. Also, there were huge tasks that could not be broken down. That's exactly where the short coming of scrum/agile. Also, in most projects there were for sure huge, hard and important tasks that needed to be solved as soon as possible. But in scrum/agile, the team tends to pick the small, simple and easy tasks first as it would make the metrics nicer. So when they finally have to pick those important hard and huge tasks, it would be most likely way too late as there were already too much done in the wrong way.