Uncapping the mana available to players at the start of the game makes it more reasonable to allow potent attacks on mana, like Wasteland, Daze and Armageddon, adding a whole new strategic element to the game
However, the card's integrity isn't affected and can still be played at tournaments when sleeved
You can't discard cards from the top of your library (for example, to activate their channel abilities)
Curses give enchantment decks something aggressive and directional to add to the buff, stax, and value cards that populate these decks
Vintage collectors chase Base Set and WOTC-era Charizards as the foundational pieces of the hobby, the cards that defined what Pokemon collecting meant before the term "investing" was ever applied to trading cards
It doesn't matter that it's impossible to build competitive decks if you just started playing, because the only reward is more cards