Why was Greninja unavailable in Pokémon Sword and Shield despite having won Pokémon of the Year?

Back in February 27, 2020, on Pokémon Day, I knew that Greninja won first place with 140,559 votes, making the #1 most popular Pokémon overall during The Pokémon of the Year 2020 event by Google and The Pokémon Company. However, unfortunately, it was so disappointing to most fans that Game Freak declined to include Greninja as available in and transferable to Pokémon Sword and Shield, even including as of both the Isle or Armor Crown Tundra updates, until in the 9th Pokémon Generation in which they have included Greninja as transfer-only in Pokémon Scarlet and Violet but then later as available in The Hidden Treasure of Area Zero, Pt. 2: The Indigo Disk, even though Greninja, the one with his Battle Bond ability can no longer activate his Ash-Greninja bond phenomenon. Now I wonder why you think that Greninja was made unavailable and untransferable to Pokémon Sword and Shield despite having won first place overall in the Pokémon of the Year 2020 event? So, please let me know, thanks.😉