No, not at all. The walled garden feature allows you to specify rules that apply to unauthenticated users, allowing them access to resources without logging in.
Read
http://www.mikrotik.com/testdocs/ros/2.9/ip/hotspot.php, specifically the section customizing HTTP servlet pages.
request for "/login" page
if user has successfully logged in (or is already logged in), alogin.html is displayed; if alogin.html is not found, redirect.html is used to redirect to the originally requested page or the status page (in case, original destination page was not given)
explains a) - setting a hard redirect in alogin.html forces that pages after successful login, since it will be displayed at that point.
login.html - login page shown to a user to ask for username and password. This page may take the following parameters:
[...]
dst - original URL requested before the redirect. This will be opened on successfull login
explains b) - rewriting that parameter to something hard set replaces the redirect after login with whatever you set it to instead of redirecting to the URL the user originally requested.