Some of them have powerful abilities that can lock out an entire opposing strategy, such as Gaddock Teeg
Panharmonicon is already an extremely powerful Commander card, and Virtue of Knowledge provides you with almost identical benefits
Once in play, Alhammaret's Archive makes any underwhelming card draw effect into one of great potency, while turning an already powerful card-drawing ability into one with no equal
Giving all your dragons +3/+3 for just 4 mana is an absurd rate, especially when you have multiple creatures already on the board
That shuts down Treasure tokens, Clue tokens, Food, Blood tokens, and many more, not just as utility, but as combo pieces
Wizards later allowed Burchett to use different cards with similar messaging on them after pressure from fans