Riiiiight, because multiplayer gaming took off as soon as Pokemon hit the market. The game is single player. If we're being honest, Pokemon was the first game to make fans pay twice long before in-app purchases even existed.
Now, Nintendo is going in the opposite direction of EA in making some downloadable content pay-what-you-want or where you can pay less money as you unlock the game.
Also, Amiibos are collectible figurines. Many people pay money for those even without the digital features.
If you think the different versions of Pokémon were made to sell you the game twice, you are wrong. They absolutely were made to encourage multiplayer trading. In Japan, the 150 were spread across 3 versions. Also, some cannot be obtained without trading because some only evolve after being traded.
All of that was deliberately engineered to encourage trading via Game Link cable. I didn't witness or read about it, but I bet Japanese school buses had dozens of kids trading Pokémon every day for many, many years.
They consolidated to only 2 versions in the USA because the Game Boy was not nearly as ubiquitous here (at the time).
[edit]
Ah. That's right: The events. Trading and battling encouraged. It was the only proper way to get Mew (#151), though you could use a cheat device or glitch the game to encounter Mew. They had the events all the time, so there were lots of opportunities to get Mew.
Later, things like "Surfing Pikachu" were given at events.