strut braces do what they say, they brace the chassis.
They do not affect the workings of the suspension compoents, but rather plant their fixing positions so that chassis flex becomes less of a dynamic variable during cornering.
Modern chassis are pretty stiff and have engineered in degrees of flex for certain applications. So you can either help or hurt the way a car handles. Besides, road tyres dont generate enough lateral G to flex a chassis that much.
Race rubber, high speeds and high power are totally different things all together.