Clearly, there wasnt a convention in place, so we cant make any pattern out of this
Brawl Not Legal Vintage Legal Timeless Not Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Not Legal Toolbox Buy This Card Notes and Rules Information for Gale, Waterdeep Prodigy: Choose a Background is a variant of the partner ability
When he entered college and got his hands on a little more money, he started researching on eBay and it snowballed from there. He started with US cards, but quickly saw that the real value resided in Japanese cards, especially the limited promotional ones like the Illustrator
Consign to Memory A super common sideboard card in Modern decks, Consign to Memory counters big Eldrazi, sure, but its also a 1-mana answer to a storm win, as it answers a card like Tendrils of Agony
In a deck with real cards, your proxies may still feel a bit different in a sleeve