Interestingly, the same logic applies to vaccination rates. Going from 0% to 5% vaccination has no impact on the course of the pandemic (except for those few vaccinated people, of course). Going from 75% to 80% has a much larger impact, and could stop the pandemic in its track (depending on R_0, and many other real-world complications of course).

(And the reason is just the same: what matters is the remainder.)