It was never good for the game to allow any player at all to fill the board with cards that can be used to constantly trigger abilities and combo off without playing cards in hands and paying mana.

It just turned the game into a big mess. Resources management should be a factor in a trading card game and you can basically eliminate that component by just playing such cards. That should never be the case.

Second cards such as Sheoldred, the Apocalypse, Rotmouth Viper, etc. who has an ability guarantee to trigger at least once per turn without any mana cost or life total cost.

Third you should NEVER print cards that are designed to combo with other cards in an overpowered fashion such as the prowess or valiant cards.

Fourth you shouldn't be printing cards such as Painful Quandry which punishes the opponent for playing the game without any addition mana input by the person who played it should never be printed. If anything the player controlling to should have to discard a card, pay some amount of mana, or pay other cost each time it would be able to trigger just to keep it from being a single card that defines a game. (It's bad for this game's quality to have a single cards or pair of cards that just define the entire game when they're in play). It's also bad to have cards like Sytheclaw raptor that does 4 damage to a player just for playing a prominent card type in all for formats, instants, during an opponents turn. One card being in play entirely redefines the gameplay. Again. Bad design. Should never be done.

Things like this just make the game less for the person who's not playing the masturbatory deck that runs these cards.

Combo decks and fast aggro combo decks should never be so common in a standard format because they just end up being masturbatory and ruins the game for the person playing against the deck.