Engines are engines.
And all cars have a redline. Redlines used to be set to avoid the first major mechanical complication that arrives due to high rpm - valve float and the possibility of pistons kissing valve heads. Perhaps some cars have them set lower in the interest of longevity, but that brings me to my point.
More revs equal more stress on all components. Not just the 'obvious' stuff such as valve springs and conrods, but things like water pumps which are (generally) geared off the engine. A pump that really is designed for tootling around town isn't really going to enjoy running at max condition at high frequency. But who knows what parameters it was desgned to....[On a modern car, I don't think it'll cause damage, but just increase wear and thus maintenance becomes more important, so keep thrashing it, and keep changing the oil
)
Finally, to the point. If we accept that redline is the point where the manufacturer has decided(for whatever technical reason, be it valve float or increased bore wear or whatever) that beyond which damage may result, it provides a good baseline to look at things ceteris paribus (as mentioned in Thomas' post). That is, it implies that running at 50% of redline should hold no fear for the engine. And it also implies that at 100% for extended periods is not going to be much good for your engine...whether a Toyota 4 cylinder, a Keith Black V8 or a lovely SOHC Ferrari V12...it's just that the revs will be different.