The MPL uses "distribute" in the sense of delivery of a copy of the software to another person or entity. We do not use distribute to mean "make available" in the sense of "making functionality available over the web without delivery of a copy of the software." So e.g. in a web-based application, the code which runs on the server is not 'distributed' to the user, but the code which is sent to the client (e.g. HTML, CSS, JavaScript) does count as 'distributed'.