What kind of systems are people imagining when they picture 'the majority of web apps'? In this thread, I see people citing HN (a simple bulletin board system)

What kind of systems are people imagining when they picture 'the majority of web apps'? In this thread, I see people citing HN (a simple bulletin board system); or sites that will get linked from HN and have to handle load - so, presumably blogs, or CMS-backed marketing sites, maybe with a sign-up form or a single product ecommerce storefront? Sure, I can buy that you can run a pretty robust bulletin board or CMS on a single server. PhpBB and Wordpress with a Postgres backend will get you a long way. But if you think that's what all web apps are like, you're not thinking anywhere near big enough. "I've seen some stuff that's over engineered" is not evidence for "everything is over engineered".