They ask for a license to store, display and publish your content, but this is explicitly limited to the use of operating the service. They need that license so that some user does not sue them for copyright infringement after uploading their own pictures and clicking "share".
Instagram/Facebook take a much broader license, which includes sub-licensing rights to third parties, including for profit and unrelated to the operation of Instagram itself.
They ask for a license to store, display and publish your content, but this is explicitly limited to the use of operating the service. They need that license so that some user does not sue them for copyright infringement after uploading their own pictures and clicking "share".
Instagram/Facebook take a much broader license, which includes sub-licensing rights to third parties, including for profit and unrelated to the operation of Instagram itself.