Some projects have different requirements, and some only require a single person who is a jack-of-all-trades.
Back in the days of the home computers( C64, Apple II and Spectrum ) a single person or "lone wolf" was able to make a small game and get it published. Floppy disks and cassettes were cheap enough for a lone wolf operation and yet as Cartidges and CDs made their entrance, the quality of games sky rocketed not to mention their expense( CD obviously became cheaper over time ). For those old, limited home computers the game's quality was acceptable, but with the power of carts and CDs players came to expect T2:Judgement Day-level graphics, soundtracks that rivalled Blade Runner and the game to have greater sized levels and content. Oh, full-motion-video was the big thing too, so one needed a background in music and commerical video broadcasting.
Suddenly that lone wolf was not only fighting the programming but the increasingly complex tools required to create the art, music and game levels - let alone the skill required to produce work to an acceptable standard. And the tools were not cheap either - for example, one did not have Blender back in those days, and chances are your 3D package would cost a couple of grand.
So, no, the solo-developer was no longer a recommended path.
Thankfully the internet and mobile phones came to the rescue as all most of us need is a "quick fix" rather than a sprawling epic like Command & Conquer or Skyrim. Also, Unity and Game Maker arrived to take care of the game engine woes, Digital art software became more affordable and even free in some cases.
And now lone-wolves are a thing once again. No, they will not make FarCry 5 on their jack jones, but games for mobile or browsers - where the idea is just fun for short sessions - are feasible.
Speaking personally, I'm going it alone on a Myst-style game( ditched Android phones for the Oculus Go...which is technically a glorified Android phone. DOH! ) but I would fancy joining a team to make 3D models just for the experience...