There could be many reasons for this such as:

1. Certain software that needs to run on the computer
2. Company image, They may want all of their employees to have similar looking laptops
3. IT purposes, it’s easier to take care of a system of similar laptops than one where they’re all different

I’m not saying all of these are good reasons but these are just a few of the ones I could think of.

Neither of these are very good at all if I were you I would look into getting a used laptop that is more powerful.