Yes, a single 1 star every 12 visits would drop a host down to 4.66. However after just 3 more 5 star ratings they would be up to the “acceptable” 4.7+. If they get another 12 ratings that are all 5 star they will be up to the magic SH 4.8. If someone is consistently getting at least one out of 12 1 star ratings a year and more than one sub 5 star a year keeping them at 4.5-4.6 range I would have to question what they are doing to earn those ratings. A host trying to raise their ratings isn’t going to do it by continuing to do exactly what they have been doing and just blaming the guest.
If I were trying to raise my rating I would definitely try to host more than 12 stays a year. Maybe if they have a two night minimum they could change to 1 night. Or quit having days off between bookings. A rating from a one night stay weighs the same as a rating from w 10 day stay.