Everyone has a very different experience of adoption - I'm sorry you have been through so much pain adopted
I absolutely would fundamentally disagree that we shouldn't have adoption. Not because it benefits me, because I would be my kids guardian if that was genuinely best for them. But for their sake, because I truly believe it is much better for them than guardianship. I don't have to make an educated guess with my eldest though, who is very vocal about the fact that adoption was the right thing for her, the most positive move in her childhood. It's not sunshine and unicorns and blah blah, no way. But it was the best option of the available ones, and has had a lasting positive impact. If someone in power were to suggest that guardianship were the better option in cases like hers, she'd be straight up writing angry letters and setting up petitions. She would be far from alone. I hate the thought that someone could deny that to another child in her position. But we need to do better at identifying children who would benefit from guardianship vs. adoption.
It's not about ownership. In those terms, children belong to no one at all, but themselves. But they are mine and FAR more importantly, I am theirs . I have made the strongest statement possible to them and the world that I belong to them. They can count on my love, on my dedication, my worries and nurture whether from near or far, forever and ever. In that sense, they own me! If you wanted to talk in terms of ownership (which I don't but my DD1 might) my DD1 would question why her birth parents should have legal status and 'own' her when they were so abusive and how could it not be better to cut the legal tie to ensure her protection throughout her life?
In terms of contact, my God I was so naively positive when I signed up to adopt. I was all about maintaining connections. I've learnt the hard way why that doesn't work out in reality
The situation with soiling etc might sound unusual but in todays adoption, it's so sadly not at all unusual. Anecdotally I've known very few families for whom it's worked out all positively for the child. Because it's not a relinquished baby situation. Contact often means inviting chaos, abusive dynamics etc back into the childs life, unless carefully managed, for instance by vetted letters, and even then it can sometimes cause real problems. Which is why we've moved to a situation where vetted letters are the norm and visits are limited to case by case basis where there's evidence this might actually be beneficial. That said, I've found sibling contact much more beneficial on the whole, though still fraught with issues.
They did some extensive research in the US, mainly around private infant adoptions, which found one of the key predictors of contact which was beneficial for the child, was that the birth parents supported the adoption. This doesn't happen much in the UK. And guardianship won't help that situation because the birth parents won't support guardianship either if they want their children living with them.
Ultimately for me it comes down to, adoption is the right move for some children. That being the case, it's wrong to take that option away. The more options on the table for a child, the better our chances of getting it right overall. The less options on the table, the less chance of getting it right overall. So I supported Special Guardianship coming in in 2005 as a new and extra option for children. Not superior or inferior to adoption as a concept, but another option which individually will be better or worse.