Yes, I'm aware that's what's usually quoted.
But seriously, what does it say?
It says all Scripture is profitable. But that is not the same thing as saying Scripture is the only thing that is profitable.
Honestly, Orthodoxy agrees with certain iterations of SS.
But that verse does not say to jettison everything not in Scripture, that all doctrine must come from Scripture, or anything else. One could argue sufficiency from that passage. But sufficiency can be found in much less than the entire Bible - it would be possible to pull out a few verses that in themselves would be "sufficient" meaning salvation is possible.
Not to mention, that passage does not and cannot refer to the New Testament. Would you argue SS based on the OT canon only?
I'm not trying to be snide, but in carefully and honestly evaluating Scripture, SS isn't there. And by many people's understanding of SS, that fact alone would automatically invalidate a doctrine.