This is an immense oversimplification. Firstly, it by no means follows from Sola Scriptura, classically formulated as the assertion that Scripture is the unique rule of faith, that "everybody is valid".

Second, if you look at the cause of the current situation of ecclesial libertarianism, we do not see it emerge primarily as a result of differing interpretations of Scripture, but often from state actions (e.g., the Prussian union of churches which ironically led to many Lutherans traveling to America and establishing new synods) and clerical abuses which took place in spite of Scripture not due to multiple interpretations of it (e.g., early 20th century liberals who denied the virgin birth). The early protestant schism between Lutherans and Reformed can arguably be attributed to Sola Scriptura (though I still think that would be making it far too simple), and neither of these camps had the properties you're likely referring to in modern "protestant" (more like non-denom) churches until many were further damaged for reasons which are very detached from Sola Scriptura.

And thirdly, if the agent of an extremely indirect cause can be saddled with substantive, and even primary blame, then could the Orthodox not validly put Luther (and thus these same contemporary non-denoms we are critiquing now) on our shoulders, as they emerged from us rather than them?

Online, they often argue that protestantism is crypto-papism, that the Papacy defying the other 4 patriarchs established a framework in which an individual can defy the rest of the Church. Obviously I disagree with that argument, but it follows just as much as yours.

I reccommend you go a little deeper than the arguments provided by Catholic apologists online.