Doesn’t help much in terms of privacy. But still is very important. https://www.gnu.org/philosophy/who-does-that-server-really-serve.html

For a bank or any system you would not have control over anyway, it does not have to be open, only the client software you run on your computer should be. But messaging, document editing (like Google Docs), etc. are personal tasks that could be done via a local program, so a remote program should be give you freedom from it’s provider.