Defeating certain enemies can earn you new cards and sometimes even the opportunity to improve or outright transform your existing cards
Depending on the context of the format and the resurgence of good combo decks in the future, I can see Force of Negation being played in more maindecks in the future
Each Universes Beyond crossover (Final Fantasy, TMNT, Avatar, Spider-Man, Marvel) releases play boosters, collector boosters, commander decks, bundles, and often scene boxes or special bundles unique to that set
Yawgmoth decks play a methodical game, assembling disposable creatures while controlling the board
In fact, I would argue that his deck is actively bad, mostly because he has so few ways to interact with the opponent and has so few burn spells