This is part of core so it affects every site made in MODX.
You are correct, however, this is not MODx's issue. In order to be compatible, MODx must handle URLs according to the server parameters. Friendly URLs are simply one standard implementation of custom aliasing. The URL requested still fires Not Found to the server, MODx just interrupts it,
So are System Events and Plugins. URL Params are not handled by nearly any system automatically. They are all a part of the technique known as custom aliasing. Previously to custom aliasing, all params were sent with $_GET or $_POST (even $_PUT and $_DELETE are not fully implemented).
Additionally, MODx doesn't restrict a user's aliasing needs, so they can't force a conformation. This might conflict with server settings, .htaccess settings, etc. So they give you Plugins so that you can make a custom solution.
Here's an example: some poeple want "mobile.domain.tld/path" for their sites and others want "domain.tld/path/mobile". MODx does not make the decision, that's your call. What you consider basic, others may consider a hassle and vice versa. This is also why I write many tutorials on extendable Custom Aliasing (including with URL Params).
[ed. note: fuzzicallogic last edited this post 14 years, 1 month ago.]