That's the main one, yes. Whenever I would be away for a day or two due to health issues, I'd always come back to 100+ in queue and DMs plus PNs about how people had been waiting 2-3 days and wanted to know what was up.
The editors are generally in one of three groups: there to go into the Q and publish their own and then roll out; health issues like mine or worse and can only put in just so much time; have lost interest and have backed off under the recent division and the mountain of work to be done.
Plus many are young and have families and full-time jobs so they just don't have the time to put in. A minimum was instituted. Twice. 5 pieces a day. That's it. Five. With a Q over 100, each editor only had to do 5.
That's why I spent 12-5 hours a day online. I didn't do it all in one sitting but I still did it. When I knew I was having surgery at the end of March the Q was down to 3. THREE. When I came back a few days later is back over 100 again.
You can't blame the quarterback when there isn't a full team on the field.
That responsibility falls on the publisher.