When your content, leads, and audience live on another company's platform, the value you create flows upward. It goes to their domain, their data, their business. The moment you stop paying, it disappears.
Most businesses don't notice this while it's happening. They're publishing content, capturing leads, growing an email list; all the right things. But every article they publish is indexed under someone else's domain. Every lead captured on a third party funnel page converts at a lower rate because the visitor left their site. Every subscriber they grow lives in a platform they don't own.
When those platforms change pricing, get acquired, go down, or discontinue features, years of effort evaporates overnight. You can export a contact list, but you can't export domain authority. You can't export the trust a search engine built up for a subdomain that wasn't yours to begin with.