Hotel Tango
Do you really expect the airline or indeed their ground handlers to break-down all the accumulated sector delays before the sector you happen to be flying on and explain all this in great detail!
For a start, we just don't have the time or often the information anyway. All we often know is that the aircraft is late, so that is what you will be told. As explained above. It can be much more complex than many outside the industry realise.
Even if you do depart a little late, often you may still arrive on time; due to ATC sometimes allowing short cuts. Also the Captain can quite often add some detail after you board, especially if they have operated some or all of the previous sectors.