Earlier quoted context omitted.
That's a somewhat recent addition, and it does help somewhat with the Photo library problem. It sucks if you don't have a fast internet connection, though. It also sucks if there's ever a problem with the photo library, because then you don't have a backup anymore. Maybe 240GB are enough for light usage if you store photos in the cloud. I can only say that in my experience 1TB is the bare minimum if I don't want to s…
Optimize Storage has been there since like macOS 10.13 (2017). You're commenting about M1 machines released 2020.
"Optimize Storage" is a bandaid that helps make your Mac with too little storage usable. But it's not a great solution. You'll be looking at spinners a lot. It's just not a nice experience when every video you want to look at takes a few minutes to load.