Back in the day there was an attempt to introduce "matrix URIs" as a more structured alternative to query strings: https://www.w3.org/DesignIssues/MatrixURIs.html

Of course there's nothing to stop you using URIs like this (I think Angular does, or did at one point?) but I don't think the rules for relative matrix URIs were ever figured out and standardised, so browsers don't do anything useful with them.