Not entirely arbitrary - forms that use the GET method instead of POST will append form values as query params.

For sites without Javascript, it's great for things like search boxes, tables with sorting/filtering, etc. instead of POST, since it preserves your query in the URL.

https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/...

It has always amazed me how much trouble the SPA folks are willing to go to in order to slowly rebuild just normal boring URLs with querystrings because users demand deep linking and back buttons and the like.

Or you could accept that you're probably going to need a round trip to the server and use a normal URL and it's fine.

For all but the absolute biggest websites in the world, anyhow. At Facebook or Google scale yeah it's needed.