Why raster image still be used when vector image has many advantages

I have read some posts and see many advantages of vector image when compare to raster image:

1. can be zoom or scale at any ratio.


2. file-size efficiency. Because vector image only identified by mathematical descriptions rather than for each pixels


3. can be used for designing logo, magazine because you can export to any size ...

I also searched and see that you can convert raster image to vector image with some tools. So my question is: With all above advantages of vector images, why some photo manipulation softwares such as Photoshop still use raster image.

Why don't we convert to vector image before doing something. And just convert back to raster image when we need export to some format such as bmp, jpeg ... when necessary.

Thanks :)