I’m sure lots of it is for cosmetics and so on, but isn’t some of it necessary to learn about the safety of potential medicines before starting human trials?
Yes, it is. I don’t know where your anon worked in animal testing, but in pharma, medicine goes through pre-clinical testing, then phase 0 to III testing before being released on the market. The pre-clinical testing uses animals to test toxicity, efficacy and pharmacokinetics.
It doesn’t use exclusively animals, there’s math and simulations and modelling, but it definitely uses, and kill, animals.