I've thrown parties with 100s of people and its mostly because people invite other people, for people you care less about a single DM you copy/pasted with the info is enough.

I also organize pretty large meetups with easily 500 people trying to get into the guest list and it's the same amount of work to go through the list and vet people tbh

What automation and tooling do you use? Between Twilio and iMessage python library and beeper, even if you don't use Partiful, there's lots of opportunity for software to make things less laborious.