"deal with kidney stones down the line" isn't compatible with "not good for you even small quantities"
Some of those vegetables are staples in vegetarian cuisines like here in India. There would have to be a huge epidemic of kidney stones if the latter claim was true.
Doesn't sound right. WP has this table: https://en.wikipedia.org/wiki/Oxalic_acid#Content_in_food_it.... I see a lot of commonly eaten foods with at least a small amount of it.