Do I have to blend my soup, or can I skip that step?!

Depends on what kind of soup it is. If it is a thick soup, then blend. If it is a clear soup or a soup with veg and meat, then I wouldn't. For instance, if it is a tomato soup then blended is preferable. If it is a minestrone or a beef and barley, or something like that, then you don't want to puree.

experience

If you like your soup a bit more "rustic" with chunks or bits of ingredients then leave it.
If you want a smooth, creamy soup that has a velvety texture then you must blend it and possibly strain it.
I like my soups more on the rustic side and like the bits of vegetable in a soup.

blending it just gives it a smoother texture, if you like your soup chunky then just skip the blending

skip that step if you want