I think it might help to expand on
that -- more about what you wrote -- in another, different way past how I already replied talking about how imperfect parents are the norm, where the really bad parenting is only the most visible or 'tip of the iceberg' of a vastly larger amount of less than really good parenting...where before I was simply pointing out examples of common ways people are doing poorly at parenting including even when they think they are doing ok...
Instead, here, I want to talk further about the truth in what you posted.
People reasonably think they can avoid the mistakes of their own parents....but it's far less easy to do that than people imagine or think, even when they give it some careful consideration and effort.
So, many people set out to try to do much better than their own parents....
But fail to a large extent.
Because the real mistakes their own parents made are not in the surface details such as whether they say "I love you" enough, or use 'time outs' in a good way instead of literally spanking a 2 yr old (which the child doesn't even slightly understand except as a shocking attack without any understandable cause...)...until they find themselves doing something much like that (if delayed), or just shift it from physical hitting to verbal or such....
So many parents think they are going to do much better than their own parents....
...but what happens is that they just make new mistakes, and often the new mistake is really just a new version of the old mistake, with a superficial change in detail.... Or at times some choose to do alternative common errors such as just merely doing the opposite of their parents for instance: such as the commonplace modern mistake of having no rules at all vs the overcontrolling micro rules of their own parents in a past generation...
Meanwhile, the real poor parenting is more subtle, and pretty often it's about emotional wrongs (subtle emotional things in how their own parents related poorly to them...) -- not about the superficial rules, but instead what is underneath -- about key things like not being loving, or not being a good example, or not teaching/guiding their children, or not paying attention to what a child can understand at a given age/moment in time/the particular child, or not treasuring the child as the wonderful unique person they are...and on and on...