I’ve seen this shared responsibility model only work when feature development is traded off with reliability as a business level guidance on top of empowerment of developers to own their systems fully. Oftentimes by the time things get bad with reliability I’ve rarely seen a business get out of the death spiral of bad technical debts being paid out with just interest daily and burning everyone out while feature requests flood in and customers leave unless there is massive funding (and subsequent hiring with a solid plan for enabling these engineers) growth.

Only ever seen it possible to turn around with empowered engineers that have the cycles to fix crippling systemic defects and the business has the means to support it. Otherwise it’s basically a Sisyphean task to maintain things and the business should have offshored the labor by then to save on costs if the cost-feature curve isn’t working out in growth stages.