Because they still have emotionally coerced the close friend into carrying the baby for them by using the line 'its our only option to be parents'.
That's abuse of power by using that close relationship to manipulate someones else.
I simply don't believe it's possible to have 'altruistic surrogacy'. It ALWAYS involves this emotional manipulation. And that relationship is altered by it. I do think there's a pretense that all parties are fine with it far too often. More relationships are hugely damaged by it than surrogacy advocates will admit to and many women who carry a baby and have regrets find it hard to vocalise that or feel they have no choice but to remain silent because speaking up when a child is involved is worse. Sunk costs and all that.
If the claim is actually true about it being the only way to have a baby it means they've been turned down for fostering and adoption. And you have to ask why. They aren't suitable to be parents. Red flags ahoy.
If that's not true the default alternative position is actually they are hamming up their point about it being their only option to be parents, and it's actually about them only wanting to be a parent in a particular way that suits them - and that makes it a demand coming from privilege. Poor people who are in similar circumstances can't just commission a surrogate. It's not a need it's a demand.
Fostering or adoption isn't suitable to these people because they deem these children as 'substandard' children who have been tainted in some way or it's all about the shiny new baby and not missing out on that stage (that's not about the kid that's all about the parents).
And that's forgetting that parenthood isn't for everyone - you can't have everything you want in life, but sheer entitlement is leading to the sanitising of baby trafficking for rich people at the expense of not so rich people. As I say, poor people don't commission surrogates.
Surrogacy centres the wants of adults not the needs children have. Depending on how it's done many children have their identity stolen from them as birth certificates are altered or donors concealed. This matters - the UN talks about how removing children from their cultural roots is a crime & we have massive scandals about adoption with children eventually seeking out where they came from years later often after adoptive parents have died because there is this natural desire to understand where someone has come from.
It's a monsterous practice whoever does it and however they do it. It's exploitative in what ever form it comes.
HTH