SOLA SCRIPTURA IS UNBIBLICAL
Consider the Old Testament. The principle of sola scriptura is utterly alien to the way in which God dealt with his people before Christ. Besides the fact that no Scripture of any sort was available before Moses' time [apart from occasional, terrifying incidents of direct revelation en masse, commands were mediated to his people through prophets and patriarchs). No Israelite was free to practice private interpretation of the Law, deciding for himself how he believed the text should be interpreted.
SOLA SCRIPTURA IS UNWORKABLE
Scripture alone, as the tragic history of Protestantism has shown, becomes the private play toy of any self-styled "exegete" who wishes to interpret God's Word to suit his own views. The history of Protestantism, laboring under sola scriptura, is an unending kaleidoscope of fragmentation and splintering.
“Nevertheless, there was a wide range of worldviews, of groups and individual perspectives, within the cultural orbit that was Judaism. Nonpriestly groups, perhaps including a share of disaffected radical priests, emerged to carry the banners of purity and/or popular demands. And every generation seems to have cultivated individual charismatic teachers, prophets, and messiahs. No single spectrum is adequate for mapping out these groups and their attitudes toward Scripture and tradition; foreign powers and ‘this present age’; class struggles and economic issues; perennial philosophical problems of monism and dualism, fate and freewill and the afterlife, militarism and pacifism; angels and demons.
“The reader of the NT must always bear this diversity in mind. In the first place, it requires that we eschew simplistic claims about what the Jews as a body believed or practiced,” S. Mason, “Theologies and Sects, Jewish,” Dictionary of New Testament Background, 1229.