I can also have my individual house designed by the developer, right?
That's true. But most of the time, in the planning meetings, you are sitting opposite a SALES PERSON, whom I assume has quite different interests and skills than someone who has studied designing and planning houses.
Although there might also be developers who send you a clever salesperson or an architect and let them design until you are one hundred percent convinced of the design.
Basically, it should of course be said that there are good and less good ones on both sides (developer and architect).