RSS and OPML are decentralized tech.
You have control over the news/content you read and if you want you can take the RSS/OPML it with you to another service if you are not pleased or just want to try something new.
google, fb, and twitter all want to control the content you have access to on “their” services. They want to be the gate keepers and it is not their financial interest to give support decentralized tech that prevents them from controlling the content you have access to.