Don't you hate someone who annoys you?
It's fine, all of us get that all the time, not everyone can work as a team.
There are strategies I've came up with how to avoid these obnoxious knights:

1. Elevator Campers- If they still have health, along with the rest of your team, by all means, leave the party or kick him/her (gender equality). People like these do not deserve getting sigils. However, if they are the last one alive without an emergency revive and on low health, then thank your lucky stars this guy/gal (gender equality) actually was trying to help. Check with other people if you're carrying them first. If so, let them do it.

2. Have one person bait the Harvester. It may seem like they're doing nothing, but if you get the right guy/gal (gender equality), like me, but they'll help you save TONS of time just having to dash and avoid the Harvest only waiting for your teammates to do the same to pass the Harvester back to you. Make sure they actually know how to do this. THIS PERSON IS ALSO RESPONSIBLE FOR PUZZLES TO MAKE THEM NOT TOO USELESS.

3. If you have a teammate that has a low-spec computer/laptop kill the goshdarn scarabs so they could do their job and not be an Elevator Camper.

4. Maps- you have a map (not half as useless) use it such as an elevator icon as a compass; just like in those ye olde times to like, NOW people still use references. the elevator can tell which direction you are or going.

5. under-leveled/ inexperienced players: You know this by now to remove them from your party (if you are carrying the low-level, prompt the others so they won't kick) there are times when you get frustrated with the mission, you'll need to down a tier, just simply find a friend/ guildmate of a lower tier and set it to elite. I presume the sigil count is affected by difficulty, not tiers.