Infallibility is not a power of popes; it is a protection from popes. It protects, not popes, but the Church.
Surely we all know that Christ gave promises of protection to the Church?
Two minutes: view and laugh.
Yet there are only two, possibly four, examples of popes speaking "ex cathedra".
That leaves an awful lot of writings by the popes over the years that could be viewed as mere commentaries.
Over which sat those in the seat of Moses, (Mt. 23:2) with such authority that dissent was a capital offense, (Dt. 17:8-13)
Yet in the wisdom and power of God ensured perpetual magisterial infallibility was never required nor promised, and while strong leadership is a means of unity, for good or for evil, the problem with the one duty of the sheep being to follow the pastors as superior and the supreme object of obedience on earth - versus pastors who ground the flock upon Scripture as superior - is that when leadership is weak or goes South, so do those who follow them, and souls may not know where to find salvation.
Regarding one such time, Cardinal Ratzinger observed,
"For nearly half a century, the Church was split into two or three obediences that excommunicated one another, so that every Catholic lived under excommunication by one pope or another, and, in the last analysis, no one could say with certainty which of the contenders had right on his side. The Church no longer offered certainty of salvation; she had become questionable in her whole objective form--the true Church, the true pledge of salvation, had to be sought outside the institution.
"It is against this background of a profoundly shaken ecclesial consciousness that we are to understand that Luther, in the conflict between his search for salvation and the tradition of the Church, ultimately came to experience the Church, not as the guarantor, but as the adversary of salvation . (Joseph Cardinal Ratzinger, head of the Sacred Congregation of the Doctrine of the Faith for the Church of Rome, Principles of Catholic Theology, trans. by Sister Mary Frances McCarthy, S.N.D. (San Francisco: Ignatius, 1989) p.196) .