How do we know that it didn't?
All of Rimuru's ogres were probably unique badasses to begin with. For all we know, the orcs are exactly as strong as a generic ogre.
Well, Gabiru's plan did revolve around hit-and-run tactics and not going toe-to-toe with them. So that might be exactly the case, that without the webbed feet, the orcs couldn't catch the lizardmen and make use of their superior strength.