The retro gaming community agrees with you in terms of hating SCART connector for being bulky and so on. However, it is kinda necessity now since all retro gaming community use it for a long time and generally for RGB based system it is the only option.
VGA requires H and V separate syncs while SCART allows Csync, composite sync, or sync on luma on its pin 20 which is what most people and their equipment use.
yes you can use a DSub connector but the equipment won't be compatible and the whole retro gaming infrastructure won't as well, so scart is the way to go.
using a scart switch like this one reliefs you from keep plugging and unplugging your cables. you can set them up once and will be ok. I showed in the video that this switch is reliable and has automatic switching where I just power on my console and it gets to the screen. I paired it with other stuff like RGB to component converter and so on.
As for RCA, they are reliable and also BNC but for rgb you would need 4 RCA cables at least: R G B and Csync, plus 2 for audio would result in 6! no system at all use this standard for RGB.. well PVMs use a similar setup via BNC but these are not as wide spread as normal CRTs and even modern TVs.
for me, I prefer something like a DIN connector. it is really small and reliable with enough connectors for everything.
you can't satisfy all people... that we can agree on.
even digital video such as HDMI connector people hate it and prefer DisplayPort for having locking pins...