If you arent aware, you completely exile an opponents library with Helm of Obedience and any one of those, which is certainly potent
At the same time I have sink time and money into grading which is another cost that eats into the thin margins. Maybe this is my own personal experience but I feel like a lot of people will have the same experience as I do
You get what kind of deck Goblin King is going to lead to
They included Vanguard of Brimaz (Born of the Gods, 2014), Eternal Dominion (Saviors of Kamigawa, 2005), Pegasus Stampede (Tempest Remastered, 2015), Oubliette (Double Masters, 2020), Man-o-War (Modern Horizons, 2019), Brothers Yamazaki (Champions of Kamigawa, 2004), and Brain Freeze (Vintage Masters, 2014)
While it has always been a part of the game, the collectibility of Magic: The Gathering is front and center nowadays