פירוש על קידושין 78:4

R. Judah interprets our mishnah so that it teaches not that one mitzvah earns one a long life, but that if one has more merits than sins he earns a long life and the world to come. In other words, any one mitzvah can “put one over the top” in the overall reckoning. Since one does not know how many mitzvoth and transgressions one has performed, the wise course would be to continue to try to perform mitzvoth.

The mitzvoth listed in the baraita must have some sort of special power, for if not, what does this baraita teach us? But, the Talmud asks, is one rewarded with a long life just for performing one of these mitzvoth!
Since that seems absurd, the Talmud interprets the baraita to say that if one’s merits and faults are even and one of these mitzvoth is part of one’s merits, it tips the scales. But alone, these mitzvoth are not that powerful.