The review, which was led by former England captain Andrew Strauss and published on Thursday, proposed a six-team top County Championship division from 2024, with a 12-team second division split into two conferences vying for one promotion place.
It also advocated for a reduction in championship matches per team from 14 to 10.
"Strauss's high-performance review is equally unworkable as far as county cricket is concerned," Filby told the BBC on Thursday.
"When looked at through the lens of high performance it is exactly what the game needs. But we are not only looking through the lens of high performance. We are looking through a financial and commercial lens.
"We are looking through the eyes of our members who have cricket that they want and we're looking very much through a variety of angles that is not just high performance."
The proposals involving a major overhaul of the domestic schedule need the support of at least 12 of the 18 first-class counties to be implemented.
Surrey's director of cricket Alec Stewart said reduced game time would allow cricketers to perform at a higher level.
"Once the energy drops your performance drops so you are trying to maintain the high performance, which is what the review was all about, so it is getting that balance right," Stewart told the BBC on Thursday.
Essex chief executive John Stephenson said the proposed changes would not benefit England's test side.
"In my opinion reducing the amount of red-ball cricket is not the way to produce better test cricketers," Stephenson told the BBC on Thursday. "Certainly from an Essex point of view, we wouldn't want to see a reduction in the amount of championship cricket."
