If they hadn’t forgotten their mounts, they might not have been too slow, though. It’s a circular problem.
Of course, among the weapons that might be left behind are the powerful Skull Lord Staves, which were long thought lost. And players can also pick up new styles of weapons, new Stronghold decorations, and new PvP gear. In short, there’s lots of good stuff to be found in Chult, and sometimes attackers just leave it lying around after the fact before explaining that they “forgot” to bring it back.