There’s no problem with a ton of people posting. The issue come in with too many people accessing the site at the same time. If I posted a link to a forum post, and 20 people clicked it at once, that sudden spike of traffic could bring the server crashing down. The easiest comparison I can think of is that of the DDoS that the East Coast got hit with on Friday. But only happening once, and on a muuuuuuuuch smaller scale.