It seems misleading to call Smriti "scripture" in the sense that's understood in the West. They're texts/literature connected to religion in some loose sense but encompass all sorts of subjects, are full of contradictory claims, and were never seen as exempt from criticism and revision, particularly over long spans of time and changing social customs. Nobody here is denying that some Hindus have historically endorsed and practiced caste discrimination; the meaningful debate is whether these things are representative of Hinduism itself, as in the religion and belief system.