Considering I played SIMCGA games on hercules on XT and 286 into the early 90s in the US, probably more common than you think. It wasn't long until the bottom of the market dropped out and VGA/SVGA cards became dirt cheap affordable. Although the monitor was the largest price shock for some time after that. Getting a good monitor that wasn't just a repurposed CGA quality tube was a thing in the early 90s. So yeah, IBM CGA does feel like an aberration of them trying to break into the home computer market in the early 80s (which they tried again with pcjr). Many people that looked at IBM were fine with mono or if they could afford it, when they came the high res screens for a graphical workstation. I think the older parents to some of us likely looked at these early color computers, with few colors and grainy display as really catering to be a toy, and wanted something a little faster and sharper display. But yeah, the 90s really did bring the switch to Windows and drove costs down for the higher res, more colors, when it wasn't so limited anymore.

I find it quite funny I held onto a CGA/EGA display, and cards, then one day plugging it in and seeing what it could do, and I was like, this was pretty neat for playing some games I remember. Of course those who had color systems back in the 80s, I remember trying out different games in color too and was amazed how it was different, so I guess I never really got tired of the games or developed a hate for the color palette dipping into it periodically.

I cut my teeth on a IBM CGA around 1988, I was then maybe a 7yo. But my really first PC of mine was in 1992 with SVGA.
I was playing games from late 80s and up until 1992 obviously, and then 93 and 94 until the poor 386SX 25MHz couldn't cope no more.
But for every single game that allowed it I used to love to try every modes CGA, EGA and VGA, my card didn't have Hercules emulation.

Never did I ever saw in front of me an IBM PC or compatible from the 80s attached to a composite monitor or tv.
Am I correct in assuming that the majority of people in USA and Europe had the same experience?

I pretty much grew up with VGA, too.
I knew about Hercules, however, due to my father and his old PC electronic books.

To me, CGA was that low-res mode with the funky colour palette.
Or, in some situations, the monochrome hi-res mode.
It was the highest resolution mode that GW-BASIC (aka BASICA to me) supported.
Some vintage chess games and simulations used it.

Btw, here's another weird PC, SAPI-86, with CGA via Composite. Language is Czech?

Seems to be some machine control system or embedded type.
It uses the card/backplane design, as it had been popular in the 1970s.

https://www.youtube.com/watch?v=BSom6GEWrJQ

https://www.youtube.com/watch?v=gxKmiOngBaw

Edit: What makes me wonder, how did people get colour out of this? It's a PAL country, if I'm not mistaken.
Then there's the 50 vs 60Hz difference. Sure, it's possible to adjust this via knob on a video monitor, did this many times myself.
But the monitor in second video link seems like a monochrome TV set (has channel buttons).
Even if it has a video mod, the knob for v-hold likely isn't available on the outside.