I was as big a Pokémon freak as anyone, lived in an extremely rural area, and still managed to complete the Pokédex without duplicate/paired games by trading with friends. (And nobody had to complete the Pokédex anyway! The games had a complete storyline without it.)
That was something that played on Pokémon as a social phenomenon. And, more than that, you didn't absolutely need to do that to play and enjoy the game. It was a multiplayer element. If you were a diehard, yeah, you could buy a second Game Boy and a second game, but that would require playing the full game twice to get all the exclusives in both. That was beyond what the developers expected the player to do. All of that would make the game harder!
On the other hand, players of FTP games are encouraged to make micropayments, which make those games "easier."
