The messaging on boosters has been awful. First, a lot of coverage of scientists talking outside of strict medical benefit of boosters. While it's been pretty clear for a while that boosters are medically helpful, there was a lot of, "scientists aren't sure whether boosters are necessary." And a lot of scientists and policy makers were looking at global costs/benefits, as opposed to the benefits for the individual patient, and concluding, "it's more important to give someone in a 3rd world country dose #1 than to give an American dose #3."
At the same time, politicians and government agencies were afraid of discouraging confidence in the vaccines. They were afraid if they pushed boosters, it would be a signal that the vaccines aren't really working, which would discourage initial vaccination.
But we've known for a long time now that boosters are indeed beneficial to patients. The evidence has continued to grow. Even for younger people, we are seeing growing evidence of the benefit of boosters.
The horrible messaging is going to hurt us this winter. For a while, we should have been treating this as a "3 dose vaccine" -- Not as a booster.
There is the possibility that this 3rd shot adds a lot of durability, and further shots won't matter. It's also possible that people could benefit from a booster every year or so.