You've managed to wrangle 2-5 other people into playing "this super cool card game" with you, and you've finally gotten them to all sit down at the table. As you haul out the stockpile, pass out the pens, and give the deck to the resident shuffler, you casually mention that everyone has to create a few new cards right about now.
This is usually when the complaining begins.
The Pregame is an important but almost reviled part of any 1000 Blank White Cards game. Creativity isn't easy, and it becomes quite difficult when demanded. Any excitement for actually playing the game can quickly fade, and cards created as a requirement aren't always up to snuff. Much like the Endgame, the Pregame is seen by some as being better cut out altogether.
And just like Endgame removal, that's missing a few important points.