I don't think the lack of DVD playback or online had much impact at all. I think that if the Gamecube had stronger titles that created an actual buzz, then the system would have sold better. There was not one single Gamecube title that was really a must have. GTA3, Vice City, and San Andreas were must have titles.
People talk about games like Eternal Darkness, Pikmin, and Baten Kaitos, but games of that tier or higher were MUCH more populous on the PS2; you had Persona, Monster Hunter, Katamari, Devil May Cry, Onimusha, Burnout, Twisted Metal, Tekken, Okami, DDR, Max Payne, God Hand, Sly Cooper, Rachet and Klank, Guitar Hero, Dark Cloud, Jak, Odin Sphere, Disgaea, Phantom Brave, Suikoden, La Pucelle Tactics, Rogue Galaxy, Silent Hill, Star Ocean, Atelier, Fatal Frame etc.... That's before getting into the core tier titles like GTA, Kingdom Hearts, Final Fantasy, Metal Gear Solid, Shadow of the Collossus, God of War, Gran Turismo, Dragon Quest, etc.. All of the games that created buzz that generation were on the PS2, the big titles were the GTA ones.
I describe myself as a little dose of toxic masculinity.







