“IMO if no embryos are discarded and all are implanted, there is nothing ethically wrong with it.”
Your opinion doesn’t matter. Your opinion doesn’t decide ethics.
“To say otherwise is to argue that no medicine should be taken for anything, and only faith healing should be used.”
That’s as asinine as thinking your opinion decides ethics. IVF is not medicine. It’s a procedure and it leads to immoral and unethical actions.
If I take one egg and combine that one egg with sperm from her husband and then insert that fertilised egg in the mother the egg came from that does not lead to immoral and unethical actions.
The couple is married, they both used their own sperm and egg, and no eggs were discarded. Nothing unethical about that situation.