What was "rude" about how you learned of this? It's simply a website and a BP.
The DL website clearly states that T-90 is the deadline for baggage. T-60 is the deadline for document check. Also, note that the gate deadline is T-45 at BDA. I am not certain about whether the counter can waive the T-90 bag drop deadline, but I do know that the system shuts down at T-60 and if you are not processed, you will not be. That is largely because the counter staff are the departure staff and need to be up at the gate and downstairs for boarding by T-45.
The process is a quite strict. Not only do you have pre-clearance by CBP, but BDA security rules are tougher than the US, there are not that many lanes and the lines can be quite slow. Finally, because of the layout of the airport, there are at least two more brief document checks, sometimes three, between the gate and the aircraft. All of this is required so as to permit the aircraft to arrive in the US and clean and thus not require connecting pax to clear TSA.
For all of this, it is really pushing it to arrive anywhere close to T-60 (or T-90) with bags. I would give yourself an extra 30 minutes for both deadlines.