When it comes to mainstream silos vs the independent web and the growing options, this is my constant conflict:
God damn it this is all crap, not just ethically but the design is terrible; ads, unreliable performance, genuinely bad UI, etc.
What does it matter; if the goal is to share to as many people as possible then just swallow the terrible option as a basic broadcasting tool whilst putting serious energy into the good options.
Life is too short, just use the popular one, invest time and energy in physical spaces, and save the ethically minded digital activity for stuff like security and identity.
Life is too short to NOT make the ethically good decision. Better to sacrifice some shallow things (in this case there are plentiful non-Instagram options for good and better photographers) and live a life knowing you made as many good decisions as possible.