Pablum is a cereal made from ground-up grains (including wheat, oat, and corn meal) mixed with bone meal, brewer's yeast, alfalfa leaf, and a bunch of vitamins and minerals. When it originally came out in the 1930's, it was used with great success as a food for infants and toddlers because it was easy to digest and helped to fight malnourishment. Pablum was pre-cooked and dried, so that helped with digestion in sensitive tummies.
One of the issues with Pablum was that it was very bland. Kids didn't enjoy it much except as a chewing or throwing exercise, although they'd eat it when they were hungry enough. Indeed, the taste was so blah that the name became synonymous with bland. Today, pablum can also mean something that is intellectually boring.
For a good example of this form of pablum, feel free to pull up most of the nodes I've added to E2. I'm guessing the person who requested that I fill this nodeshell for reQuest 2018 feels this way, and I do hope I've given them a modicum of pablum entertainment.