While thinking about a few business models, I more and more come to terms with user data. Having nontransferable user data in your application is excellent. For the owner of the application!
The customer gets denied an opportunity! And even the application owner could lose out.
I guess you can put it in place in various ways. The two versions I would like the most are the following.
Version A would make a central data hub available for customers. Their data is saved, and services can request access to it. Customers would be in a position to revoke access rights, at the cost of service cancellation. It would be possible to fine-tune the access, being as specific as needed.
Version B would force application developers to create unified access points. Those can third party applications use to pull out data in a standardized process. Still requiring the consent of the customer!
In general terms, you would create more opportunities for service offerings. Especially for those larger companies. SMB who are using standardized software for e-commerce as an example. Can already pick services out of marketplaces. But to get into a position where you can disrupt or leverage big players, you would need to access them.
Also, you would make it easier for new players to take over. When you have a better value proposition, and your only reason you are still locked in a relationship with a vendor is the data. Then your business model is weak, and this alone shouldn't keep customers from switching.
I know there has been already a debate around it under the "Data Portability":
The right to data portability allows individuals to obtain and reuse their personal data for their own purposes across different services. It will enable them to move, copy, or transfer personal data easily from one IT environment to another safely and securely, without affecting its usability.
The negative is in the details of implementation. The centralized solution would need a trusted authority in a global world, which isn't available today! The decentralized approach would have scaling issues and problems with technical implementation.
Privacy, Security, Technical ... the list of issues is long. Not even considering the political impact something like this would have.
The exchange of data takes place over backdoors. Getting access to your E-Mail allows certain providers to screen for buy behavior or other data. Browser add-ons allow for integrations inside websites.
More prominent standardized software solutions already leverage a unified interface from players like Shopify, offering a marketplace for add-ons to Amazon and many many more.
Interesting topic to explore!