Well, ownership implies and enables interoperability. When your profile and content exists in your wallet, everytime you connect it to a given social app, you carry it with you. From a user perspective, its a single handle for every social app that integrates with it, and from the builder perspective, it's a batteries-included content and user registry.

In this paradigm, the blockchain becomes the single public source of truth/database for everyone's content. And what you mean by 'service' is just any frontend app that consumes and presents this content in a nuanced format for its target audience. So as a builder, you can focus on creating an engaging and valuable experience for your users, providing them interesting ways to engage with each other, monetize content, fund common goods, promote or filter content etc without worrying about scaling your infrastructure.

At the same time, you don't need to rely on the blockchain for anything besides user authorization - nobody stops you from just using Lens as just another sign in flow to your existing web2 social media app and keeping your business model intact, while simply increasing your userbase.