There is a grippy bottom and there is a grippy bottom and
Complete flat sole with no "texturing" makes it unsafe to walk in damp and wet surfaces like grass, you slip. Traditional "old"
style paddock boots.
are commonly made with a "textured" sole but that texturing is not wrapped around the shoe, only on the bottom and not
thick gummy material.
Boot bottoms like that of the Arait H2O boot bottoms are more an issue.
Yes, they say they are for riding...and they offer support for that... it isn't
the "bottom" tread that is the issues...it is
the tread the protrudes around the boot and can catch on the sides of your stirrup that is an issue.
Good western "riding" boots are not
completely flat soled... they have a 2" heel or slightly more and a sole with tread on it that grips the ground and stirrup some, yet does not protrude around the boot where it will catch and hold to the stirrup sides... hence a safety issue and a possible dragging when it is harder for a foot release in a fall.