I personally believe, based on my experiences, that there are hundreds of thousands, if not millions, of Protestant denominations, and the main reason for this is sola scriptura.
Most Catholic critics of Protestantism don't place the number of denominations that high. But Martignoni's comments reflect a common Catholic sentiment, though in a heightened form.
One of the problems with that sentiment is that it undermines Catholicism. Catholics often argue for the Roman Catholic Church by first arguing for Jesus. Supposedly, Jesus founded the Roman Catholic Church and taught, directly or by implication, that it has the authority it claims to have. But that sort of argument for Catholicism requires the Catholic to argue for, or depend on others who have argued for, Jesus' existence, His identity, what He taught, the meaning of what He taught, etc. And there are many differing and contradictory interpretations of Jesus and His historical context. Consider, for example, all of the views of Jesus you come across on the web and in modern scholarship, including Catholic scholarship. The Catholic appeal to the historical Jesus as an argument for Catholicism depends on our being able to sufficiently discern the historical Jesus. If we can do so, despite all of the disagreements that exist on the subject, why should we think the same isn't true with regard to the Bible and sola scriptura? Much the same can be said about all of the disagreements concerning the existence of God, the Messianic prophecies of the Old Testament, the apostle Paul, the church fathers, etc.
Catholics should ask themselves what would happen if they were to apply their arguments against Protestantism to their own belief system. It seems that they often don't do that.
One way to answer the Catholic who cites a large number of Protestant denominations is to cite the large number of views of Jesus. Or the large number of views of the origin of the universe. Or the authenticity of the writings of Ignatius of Antioch. Or the meaning of what Irenaeus wrote. Or the validity of particular claimants to the papacy. Etc.
Maybe Catholics wouldn't use so many suicidal arguments so often if they were more involved in Christian apologetics. Evangelicals have been at the forefront of that work, while Catholics have been more concerned with other things. And it shows.