About the “don’t hate younger versions of yourself”- I can see that with ignorance and inexperience, but wouldn’t it make sense if someone used to be violent and/or mean to hate who they used to be?
I don’t think that hating your former self helps in that case, either. Some people have a lot on their conscience for which the only appropriate reaction is horror and atonement. That is not the same as hating yourself. Self hate will not help.
Partly because - the person who did and believed all of those things is still you. You will always be someone who once did those things, even though you now know better.
I think that kind of past creates obligations. You have to be able to face what you have done, and do work fighting the kind of evil you were once responsible for. That work has to be done with love.
Part of those obligations have to do with - finding ways to communicate to others who are cruel in the way that you once were that it is immoral and inexcusable to do those things.
I don’t think you can do that if you hate them, or if you see them as worthless and irredeemable. You were not worthless or beyond hope when you acted that way. You learned to stop. You are not unique in that regard. There are others who can stop, and there is work you can do to make that more likely.
It doesn’t mean that you have to renounce all boundaries and let mean people hurt you, or that you have to be close to people who are doing the kind of harm you once did. But it does mean that you have to do things beyond feel disgust. Hating your former self is a cop-out.
Push come to shove, you have to live with yourself. Hating yourself won’t make your past go away, it won’t undo anything you’ve done, and it’s not a way out of your obligations going forward.