That doesn't match my recollection. The Gameboy is a early counter example: it was black and white during a time where the game gear had color, yet the Gameboy was far more popular. Also I believe the Xbox was more powerful than the GameCube.
The Game Gear didn't come out until one and a half year later. It's easy to see how it wasn't even remotely practical to release a color handheld system in 1989, and it's easy to argue that it wasn't practical in 1990 either, but Sega did it anyway.
So when the Game Boy came out it was easily the most powerful handheld system on the market (admittedly by virtue of being essentially the only one worth mentioning)
Also, the color screen on the Game Gear wasn't that great and the battery life was terrible. I think Sega had realized this, because later on they were selling an external battery pack as an official accessory.
I remember thinking the commercials made it look cool when I was 4 or 5 (I vividly remember some sort of surfing game), but then I never encountered a single person who owned one. Same with the TurboGrafx-16.
"Some sort of surfing game" immediately screams California Games¹ to me. There was surfing² plus a few other sports, and it is still good fun if you find yourself at a museum/nerd house that has one.
I remember kids with the game gear. Hardly ever saw them playing because of the batteries. For a portable console I think it was a choice on battery life.
The game gear was extremely lousy to use. Too small of a screen, ate through batteries incredibly quickly, the original, external battery pack (not included) was poorly made and didn't help that much either.
And the game selection early on was pretty lousy too. Sonic was only fun for a while.
People are doing amazing things with game gear hardware as of late, though. All of that addressed spectacularly.
The game boy got almost 30hours out of 4xAA whereas the game gear got about an hour or two of life out of 6xAA. I hated that about the game gear and it meant I hardly ever got to play it.
