The vaccines create a much more potent antibody response than the titers we see in convalescent plasma. 5-10x less binding probably translates to somewhat reduced efficacy (no one really knows, but 75% vs. 95% might be a reasonable guess). Of course, this is a really complicated thing, because it's not just the immediate antibody response, but also the T-cell response, and also how quickly on a subsequent infection the set of antibodies develops and broadens even more.

We do know that e.g. in Israel where there's very high amounts of vaccine deployed and nasty variants, that case control studies show a large effect still.