Do I still need citations?

Yes.

Even for well-established propositions.

Not because readers doubt them,

but because scholarship requires attribution.

For example

Weber (1905) argues that rational capitalist enterprise presupposes formally free labor.

or

Polanyi (1944) argues that the emergence of market society required prior institutional transformation.

or

Thompson (1963) examines the historical formation of the English working class.

Even standard knowledge is normally supported by citations in academic writing.