After almost 4 days of searching I somehow stumbled upon this plugin and finally found something that does exactly what I was looking for: it completely blocks users from your dashboard and redirects them to the main page.
Please note the following:
-My website already has a custom profile page where users can edit their profile.
-When users log in, they can see to links: log out and their name (which leads to wp-admin/profile.php). Although Subscribers will still be able to see the link to profile.php, they will not be able to access it; directly or indirectly.
Too bad that this awesome plugin is no longer being supported.