Even if you haven't, the core concept is simple enough to understand if someone or something suffers some sort of ailment, it's going to negatively affect them in some way
Imagine cereal boxes contain one random coupon and you want the full set
From here, proceed to make Marincess Coral Anemone and revive Cambro, locking yourself into WATER monsters
That makes it impossible for your opponents to pull ahead in resources and offers 2-6 more cards per turn cycle without extra card draws factored in
The Deck just didn't have a ton of options, with some other common Rank 10s besides the Trains being Skypalace Gangaridai to pop an opponent's card and deal 1000 damage, and even Number C9: Chaos Dyson Sphere to absorb any monster it battles as material and deal 300 damage per Xyz Material each turn, along with the previously used Superdimensional Robot Galaxy Destroyer since all these options are Rank 10 Machines you could slap Liebe on top of
Collectors who focus on hidden OCG grails often prioritize cards like this because they rarely appear in public marketplaces