With the Gnosis Safe we are aiming to build a 100% self-sovereign fund management solution. To us, it is very important, that nobody besides the owner(s) of a Safe can access/freeze funds or modify any settings, but also that users do not bear any counterparty risk. So while Gnosis provides some pieces of the the solution to improve on convenience and/or UX for the user, we also want to make it as easy as possible to go completely trustless.
So for a regular user, there are indeed a few Gnosis-dependencies today, mainly:
Hosted web interface (gnosis-safe.io)
Transaction indexer (backend infrastructure for the interface)
While it is possible to interact with a Safe contract through any means where arbitrary contract calls are possible (e.g. MyCrypto), we also created other ways to interact with Safe contracts in case one or both of the services above should for any reason cease to exist:
Advanced users can also Command Line Interface (Safe CLI) to interact with Gnosis Safe contracts.