In fact, you usually
can just send arbitrary query string parameters to a server - that's why the behavior is so common, and often useful.
Most sites don't mind or break, some sites get value from the behavior in ways hard to replicate in other ways – and those sites that don't like such additions can easily ignore them. And a few lines of code will work better than ineffectually appealing to manners, when the freedom of the web's form of hypertext, and protocols, gives the outlink authors full freedom to craft URLs (and thus requests) however they like.