They did to start.
Originally Posted by micwrecka
The EmotionChip was a special piece of hardware introduced into the system launch versions. (60GB / 20GB models) The damn system was so expensive to manufacture that the EC was the first thing removed during costs savings.
Because Sony placed "PS2 compatibility" in all of their marketing campaigns, they couldn't bail on the functionality. Without an EC to do all of the processing, Sony turned to PS2 software emulation. This was installed in the first 80GB machine ... and was last seen in the MGS4 special edition.
Software emulation proved to be so buggy that Sony ditched developer support on it 4 months into it's first appearance. The functionality would still exist, but if the game didn't work ... Sony basically said, play it on a PS2 console.
There's only 1 answer to your question
end of story