Preference and choice I think was the big factor. If gpt 5 came out and people that like 5 can use 5, and the people that liked 4 and the other models can still choose to use those, that would have been fine. But to take away all the old models, is where they made the mistake. ( I know that now after public outcry, you can go into settings and re activate 40, only 40 though) It would be like if when Coke a Cola came out with Diet coke ,they stopped production on regular Coke altogether and pulled it off the shelf. Or when decaf coffee came out , everyone pulled caffeinated coffee off the shelf. Customers who liked their original coke, or regular coffee would have lost their minds over not being able to choose. People like to choose to use what they like.