Flat out, you don't know all the logistics and issues behind their choice not to hold the flight. Its easy from your perspective to say they only had to hold it ten minutes for us. There are a lot of details and factors that go into those decisions. I'm sure they much rather would have put you on their own metal than pay for tickets on another carrier if that was the best option for Delta. It wasn't, they got you to your destination, end of story.
For someone with your travel experience, it shouldn't be a shock to have to put up with a 6 hour delay, particularly with international travel. It happens. Be glad it wasn't a full day. The reality is they already had a plan in place when you got there, and they got you to your destination with a small delay.
Your thought on how many miles this is worth puts this firmly into DYKWIA territory.
And nice job (even if it was joke, which I don't sense) for blaming the pilots for being late. Would you rather they flew an unsafe airplane? They were handed a broken plane. Not their fault.