bedliner and paint gurus..

Was looking at various roll on bedliners and all that ive seen are just polyurethane with added rubber granules. So it got my thinkin...I found a place that you can order enough rubber granules for 1 gallon of polyurethane for $12, and a gallon of oil based polyurethane tinted to whatever color you want for $22. Anyone see a reason why this wouldnt work just as well as any other bedliners? Seems to me that it would be basically the same thing, only alot cheaper...am I right?

Jmeti000