2. They're not kidding about how the guestlist can be quite stressful. Unless you're having a kampung-style wedding and you can invite a thousand guests.
3. You've probably promised your teachers/friends in high school that you'd invite them but haven't seen them since. Not obligated to invite.
4. You might have very very annoying bosses you don't even like/can't stand being around. Must invite, if they're in your team/department/division/floor.