I'm past the comment edit window, but incidentally these two Harvard pages[1,2] say that:

- the recommended daily vitamin C is 90mcg for men and 75 for women, the upper limit is 2000mcg. That's a safety margin of 22x, and exceeding the upper limit may cause diarrhoea and gastrointestinal distress.

- the recommended vitamin A is 900mcg for men and 700 for women, and the upper limit is 3000mcg. That's a safety margin of 3.3x, and even that upper limit has "some evidence that this much preformed vitamin A might increase the risk of bone loss, hip fracture, or some birth defects".

- "Sometimes people take cod liver oil for vitamin D but may not be aware it is also very high in vitamin A, beyond the RDA at 192%"

That is, even without any alternative views on it, it's much easier to go above the safe levels, easier to do accidentally, and the risks are more serious.

[1] https://nutritionsource.hsph.harvard.edu/vitamin-a/

[2] https://nutritionsource.hsph.harvard.edu/vitamin-c/