The Biz market back in the 80's was 80%+ Monochrome because Colour monitors were quite a bit more expensive and so I supect that the composite output was to cater for that market.
I got given my c64 with a Composite Green monochrome screen and I remeberber seeing a lot of biz computers being mono only (in PC land it was MGA aka Hercules GFX cards).
iirc not having the extra colour pixels made for more pixels on mono screens and the GFX looked sharper and smoother as a result.
Just to be clear: The built in composite output of an A500 is way beyond PC land monochrome. A500 composite is 64 shades of gray easily displayable at once from a palette of 4096 gray shades.
Using HAM mode or raster interrupts one can get all 4096 shades on screen at once.
To view the gray-scale screen in color one had to buy an extremely high-quality 1080 RGB Analog Color Monitor for $399.00 or spend $50.00 for the Composite color output adapter that so many of us have laying around in our closets that we have no use for.
