DVI has analog signals, and buying 24+5 can be directly converted into VGA. These four extra pins are analog signals. It's also very cheap.

You said that converting HDMI to VGA requires a large chip, which is tens of dollars more expensive.

The reason why there is no conversion from large DVI(24+ 1) to VGA is because of the existence of DVI(24+5), which kills expensive DVI at low price, and it is meaningless to convert expensive DVI to VGA.