No, MK Tour being considered "a Mario Kart game" dosent mean is MK9.

A) Nintendo never said "Mario Kart Tour is a mainline Mario Kart and the successor to Mario Kart 8. The only time they implied is even remotly "mainline" was in the trailer for the Booster Course Pass where they included the game in the "tracks from previous Mario Kart". Even then, the game IS Mario Kart, it dosent mean is "mainline"

B) Even then, being mainline dosent really mean is a numeric entry. "Oh if tour is mainline then is 9!" No, it just means is a Mario Kart game. New Super Mario Bros 2 is the third New Super Mario Bros.

Mario Party 9 is more like Mario Party 11.

Metroid Prime Hunters IS a Metroid Prime game. Is just not a numeric one