Yep. You couldn't really get Lickilicky, Rhyperior, Tangrowth (hell you needed to transfer for this one), Electivire, Magmortar, Togekiss, Yanmega, Leafeon, Glaceon, Gliscor, Mamoswine, Porygon-Z, Gallade, Probopass, Dusknoir or Froslass until the post game in Diamond & Pearl. That's a decent amount of the 107 new Pokémon that generation provided.
GS didn't just lock new Pokémon out, but other Pokémon in the Johto dex
And of course the ratio will shrink as we get more Pokémon unless they increase the amount of new ones in proportion to the previous amount, but that'd be silly.