Why sites make different page for each question?

Question

i want to ask why sites make diffrent page for each post for example if we post any new topic or question in csharpcorner disscsion board so when click on link so page appear like this.

your-thread-is-that.aspx

although we can do same work by using query string like this.

thread.aspx?11125

so any mechenisim for make new page for every post because it also use more space.

if your answer is yes so how can make new page by coding?

reply your valueable and valid answers please.