Only merit I can see to this is if they received replacement devices that failed very soon after the replacement. By most accounts this is a rare occurrence. So, "equivalent to new in performance and reliability" is accurate and defensible. Are these people claiming their replacement devices were noticeably worse than the original?
If you buy a new apple device or computer, and it arrives doa. Then Apple replaces it with a refurbished device, you are essentially robbed. The refurbished device or computer is typically sold at 10 to 25% discount.
If you purchased a new device, you are entitled to a new device as a replacement.
I've argued this point before with Apple when brand new $3000 computers arrived DOA and they offered a refurbished machine in its place. If I paid for new, then give me new.
Now, if they want to replace my new computer or device along with a 10 to 25% refund, then I'd happily consider a refurbished machine.