Well, they didn't love me, but that's a narcissistically-dysfunctional family thing, too.
But the idea that a donor-conceived child is graciously accepted by the social father just like his own would be is scary and eery on several levels:
First, it accepts the supremacy of blood ties for the parents while simultaneously denying it to the children (the father apparently has the right to not accept another man's child with perfect love, although this was his choice, whereas the child can only be grateful for being loved despite not being biologically connected, without the option of not accepting another father as her own, although the situation was certainly not her choice).
Second, it uses the ultimate trump card: "love". Love is all you need: if they claimed they loved you, or pretended they did in public, or told family members and friends they did, then what else do you need? What else dare you ask for? Knowledge and information on who you are? A connection to your actual father? The permission to feel cheated out of that? Why? Love is all you need!
Third, it posits the biological father as somehow inherently inferior - you were fathered by an anonymous donor, but "they loved you just the same"! And I should be grateful that this inferior, unknown, mysterious, dark half of me was not rejected (although it was, and often is). Where's the freedom to think of my real father as potentially superior to my social one? Mine was not a sperm-selling creep - remuneration for donation still doesn't exist in my country. I'm smarter, more successful than and not as fucked up as my parents and have talents and interests different from theirs - so, I can surmise that my biological father must have contributed to that. Where's my freedom to say "Well, I don't love you just the same and I would have preferred to have been raised by my real father, if it had been at all possible"?
Fourth, it states openly the fact that you are a back-up plan while expecting you to be grateful for the only family you know without hoping for a back-up plan of your own - meeting your donor and thinking of him as your real father.