I don't watch World Superbike, are tires a constant subject there too?
They're single manufacturer (Pirelli) offering different compounds, like MotoGP.
There is some discussion about how some rider+bike combinations work with certain compounds and not with others. But I would say tire selection in MotoGP provides more of a swing in performance during race weekend than WSBK.
Picking the wrong tire in WSBK just means Jonathan Rea comes in 2nd instead of 1st that race.
Although 2021 looks like it might be a changing-of-the-guard season. Razgotlioglu seems to be the only one capable of breaking Rea's dominance.