It is what is recommended. Antibodies from having covid are short lived on their own. you need to boost them. Basic immunology.
Covid antibodies fade from both covid and the vax, but recovering from covid elicits a Tcell response basically putting anti-covid sentries on guard in the body for 20+ years and possibly lifelong. The longevity has been shown with the Sars virus and Tcells can be tested for.
MarMema, you don’t know as the Scotts say, “Yer Arse Frum Yer Elbow”