It doesn't help that console releases per region were spread apart far enough that it horribly skewed everything back then. The Famicom is a 1983 console that didn't see release internationally until the "Famicom Boom Period" and by the time the NES hit its "boom period" the Super Famicom was near.
The SG1000 (basically a Colecovision) and Famicom released on the same day in Japan. I cannot comprehend how anyone would lump them in the same generation.
Even going by bits can get dicey. It's probably more useful to categorize the various machines at home and arcade by media type from which they played games. Cartridge/floppy/PCB gradually giving way to optical media, then hard drives/SSDs and all-digital options.
The hard part is that it’s more of a gradient when you look at worldwide console release dates. Then you throw in these sort of half generations like the early 32-bit consoles and pc games… generations can be good nuff for conversation if they’re thought of as eras.
Sometimes it's hard to cut through the noise and myth around the Atari Crash, but the most concrete consequences of it can be seen in the bewildering number of early '80s Famicom games that turned into late '80s NES games that certainly felt dated in ways that were hard to understand without context
Console generations also deliberately ignore how influential arcades and (micro)computers were in the ever evolving video game space.