I wonder if we can do everything with the pathfinders without using the shape builder.
You probably can, but will be more tedious.
e.g. deleting parts of paths.
There are perfect reasons when to use pathfinder functions. There are perfect reasons when to use the shapebuilder. Why would you want to limit yourself?
Mhhh, I see, but sometimes the tool shapebuilder make a strange vector
Hhhhmmmm. That is not particularly descriptive in a way that someone could help you. So perhaps you want to show examples.
The simple answer is no.
With Shape Builder, you can more easily apply Unite and Minus Front to exactly what you want. Considering these are probably the most used commands in Pathfinder, this is an amazing timesaver.
But Pathfinder allows you other possibilities, such as Divide, Exclude, and more. If you're not a big fan of Pathfinder, try Live Paint. https://helpx.adobe.com/illustrator/using/live-paint-groups.html