Defining FCPATH

Hello, 

I am setting project in way I'd like to have two directories available: `public_html` and `app`. 
Directory public_html would be root of domain so I would keep application, system, vendor and composer.json in app directory 
outside of http approach. So far so good. I am setting $application_folder and $system_path variables to fit new locations of respective 
directories (i.e. '../app/application'). Also I was checking other constants to see if those are affected by this change and to be sure everything is well.
I ended up with FCPATH link. 
Since I am working on Windows / wamp, FCPATH is represented as "C:\wamp\www\ci302stable\public_html/" 
and as you can see with slashes mixing.
But when I check BASEPATH there is used str_replace() function to make same case slashes in link 
("define('BASEPATH', str_replace('\\', '/', $system_path));").
I was wondering why such a function is not used for FCPATH.

Regards,