I certainly don't need to justify my reasoning for using Facebook or Instagram to you, but I assure you there are some things which are easier when you have an account. Many small businesses exclusively use FB to post updated hours, for example.

I am well aware of the privacy and social issues around using those websites. Being careful and mindful with my access and the content I let them receive (e.g. limiting permissions via a browser instead of native app, not uploading my entire life to the site, not regularly interacting with the content) is how I manage my personal risk.

If you're aware of some methods Facebook is using to break out of the browser sandbox and access my content without my permission, then by all means I'm open to review any sources you may have to suggest that my mobile browser is an inappropriate tool for restricting access.