Manual upgrade old and unused files

[Mirgen]

Hello, 

I have a remark and a related question: 

When a one performs Manual upgrade, specifically step File copy like here: https://devdocs.prestashop.com/1.7/basics/keeping-up-to-date/upgrade/#file-copy isnt it true, that files in OLD version (destination where we copy the files to) which are not used anymore, which are not even in the new version (source folder of the copy process), isnt it true that these old unused files will remain our application?

It is probably not a big deal, but why to have unnecessary files.

Thank you ion advance for confirmation, sugestions and solution