There are literally tens of thousands of other campsites and trails to hit if you want to avoid that kind of thing. Hell, even in the more crowded areas, it's straightforward to head into backcountry trails and go from hundreds of people to none.
From personal experience: Multnomah Falls, in the Columbia Gorge in Oregon, is a madhouse. Tour groups get bused in, everyone and their dog (literally) is walking up to the top of the waterfall, etc. More than two million people visit the falls every year. But if you head past the waterfall, you'll only see a few people, and after five miles up the Larch Mountain trail, there's absolutely nobody except for the very occasional weirdo like me. And if you don't like the crowds even at the entrance, there are a gazillion other trails in the Gorge that are very sparsely traveled.