Actually, that's exactly all the original Polio vaccine did. It did NOT prevent infection from poliovirus. Only .5% of poliovirus infections led to poliomyelitis, which makes it actually a pretty good comparison to COVID since most people, without any intervention at all, only had a mild illness. The vaccines were all about decreasing the chances of the infection progressing to paralytic poliomyelitis. Which the original Francis field trial results were 80-90% effective at preventing paralytic poliomyelitis. That's how they sold it. The switch to the Sabin vaccine in 1961 was because it was proven to be better at preventing transmission than the Salk vaccine, despite the risks of using a live virus. If the Salk vaccine was so perfect against all three: disease, infection, transmission... there wouldn't have even been a need to have debates about switching would there? You have made assumptions of what the polio vaccine must have done based on the outcome of reaching near-eradication. But they are just assumptions.
Sterilizing immunity, like herd immunity and endemic are words that have been co-opted by anti-vaxers and others looking for justifications to do nothing. It's based on assumptions on how vaccines work, and what was measured and studied during historical vaccine development. It's really hard to tell when people are infected but have mild or no symptoms. Even today. All people could really measure, in the past, were the incidence rates of severe disease. You can't go back to the old studies about early vaccine development and see measurements of preventing infection, because that's not what they were concerned with.
Sterilizing immunity is called a "holy grail" by experts because they know how rare it is to actually happen. It's a bunch of revisionist history to claim that the experts were touting sterilizing immunity for this vaccine as it would go against all of their education and experience. I remember seeing a whole lot of in many cases records were NOT kept regarding prevention infection as it was not part of the study parameters regarding efficacy against severe illness and safety. And people getting really upset about that part being missing. I remember a lot of "we hope it prevents infection, but we don't know." What media and political leadership said only demonstrated their own understanding or lack thereof, of how vaccines work and their own ability to be drug along the lines of "wishful thinking."
I'm pretty sure I posted this article the last time the lack of sterilizing immunity was brought up:
https://www.theatlantic.com/science...izing-immunity-myth-covid-19-vaccines/620023/
Experts talking in terms of myths and ideals, and about how far up the scale they can achieve with no belief that it could actually be 100%. Even referring to small pox as not sterilizing, although that and measles are the ones that are most normally associated with sterilizing immunity. Sure, these people who talk in these terms are going to go out and tell everyone from the beginning that Covid vaccines prevent infection. They didn't. But people would rather believe they were mislead instead of jumping to conclusions based on erroneous assumptions and wishful thinking.
