I would say the consensus mirrors the advice you've come upon thus far. I think it's ok to cite specific texts that are relevant to your research interests in the body of the SOP by name, but it's not customary to include a formal bibliography, nor is it a requirement to include in-text citations. The general assumption is that quotes are superfluous in the context of an SOP because you can safely assume that Admissions Committees are intimately familiar with whatever text you may be moved to pull from.
Ultimately, the SOP requires you to be specific in terms of the broad strokes, like your academic and research interests, why you're applying to the program(s) you've chosen, faculty whose work resonates and who are able to support your journey to the end of your degree, and how you intend on actively participating in/contributing to any given university community. You can get away with leaving citations out because the SOP is your opportunity to use your own voice to be clear and specific, rather than quotations.