You might be surprised at
a) the 'imperfect' (ie the variety of) people approved to adopt in this country... even babies
b) the impact that the fundamental rift and the impact of the antenatal and postnatal stress can have later, especially in teenage years. Likely higher incidence of genetically related disorders (which in the biological parents are a factor, known or unknown, in the baby being placed elsewhere) that may not be picked up or may be ascribed entirely to attachment disorder etc etc I have a number of wonderful friends and contacts who have adopted babies or very young children and it is no picnic as they become teenagers and adults.
It's obviously a different situation to a child who has experienced much less security etc but it isn't nothing.