This could certainly prove to be an issue, but a deck like this also needs a critical mass of velocity and moving parts
Parallax Inhibitor already did very little with a subset of cards that were only supported in a single set (Nemesis)
It earns the #1 spot because it was built specifically to solve the problem American collectors face: getting authentic Japanese products shipped internationally, reliably, with English-language support every step of the way
Some benefits of having specific Pokmon cards include: Being able to complete your collection
The combination of seeing five cards and drawing two is surprisingly potent, especially in formats that have good ramp (Sol Ring, Ancient Tomb) and where the power level between cards varies greatly (singleton formats, Vintage)
The higher the number, the better the card is expected for your deck