TL;DRNo really, stop doing it.
I’ve had more than one conversation with a client lately, wherein they describe another agency’s attempt to sign them onto a proprietary CMS: “Our team built this platform from the ground up, so we can create your site in half the time it might otherwise take!”
That may be true, and at the outset, that might sound pretty good to the client. But now:
That client is locked in that agency’s walled garden. They’re dependent on that agency for any code-level change—a reality that’s likely codified in a maintenance retainer that stretches on in perpetuity.
The progress of the platform core is limited only to what the agency can dedicate to it. An agency’s business model is very different than a product company’s business model, and that economic reality can make it challenging to consistently justify that time.
If the client wants to ultimately build their own technical team, they’re prevented from doing so because they don’t own their technology.
If the client wants to transition to a difference resource, they have to go through the arduous process of migrating their content off the platform, and reinvest to rebuild it on a different CMS. That negates any efficiency that might have been gained on the initial build-out.
For these reasons, the idea of an agency building and selling a general-purpose CMS platform feels deeply irresponsible to me, a bit hubristic, and even a little predatory. By design, you end up tethering your clients to you, and limiting their ability to mature past the walls you build around them.
So, clients, if someone tries to sell you on that approach, run. Agencies, stop trying to sell clients on that approach. If you want to gain project efficiency, build yourself an extensible WordPress theme instead.
(A P.S. for clarity: I’m not talking about custom software development here. If I build somebody a Laravel-based CMS platform, at the end of our relationship, they own that platform, and can take it to any other developer they want. I’m speaking specifically to the fad of agencies building and maintaing their own CMSes, and selling access as part of larger design/development projects. That’s what needs to stop…. Stop it.)