So are clarinets. But the heyday of keyed brass instruments was the 19th Century, and very early at that. We've come a long way since then, and today's french horns are just as reliable as my valved trumpet. Remember that the saxophone wasn't developed until about 1840 and they monkeyed around with the clarinet from about 1600 to the late 19th Century. But those are reed instruments, not brass, and the playing characteristics are different.