Although SD card is not too expensive. But who still has a few old SD memory cards in the drawer, who wants to continue to use. That’s not a problem at all. It’s just a question of where to get an image of the right size.
Raspbian, one of the most popular distributions for Raspberry Pi, is just under 4 GB in size, which is why it fits on a 4 GB SD memory card. But that can change fast because in general, all distributions get bigger with time. In addition, one would like to install some software.
Therefore, it can not hurt to look for alternatives that need less storage space.