Okay, after all the cards are translated, the Team Rocket cards have the exact same issue as Trainer's cards - they're allowing a specific deck to access obviously overpowered effects (here it's Guzma, always-on Lillie, Double Colored Energy, and who knows what else) at the "cost" of being inflexible. In fact, they're even more inflexible than most Trainer's cards.
Because the cards are so strong and because you're not allowed to deckbuild, there are two outcomes - either the deck will be overwhelmingly powerful, or totally outclassed.