htaccess for redirecting all requests to public folder in shared hosting

Could you point to the explanation via web, why it is not a recommended practice? Thank you in advance.

I don't know any articles by heart and haven't written any myself on the topic, but it's basically this:
In case your web server gets miss-configured and it dosen't read your .htaccess file or PHP for some reason don't evaluate your files, people can access everything from the url. That's what the extra security provides, you can't access those files under any circumstances from an url (as it's one level up) even if your web-server setting changes.