You bring up some great points. There are a few things to remember when it comes to choosing a solution that I would add to your comment.

First, what budget do you have? Can you spend the money on something like LaunchDarkly, Azure Config, etc.? If so, then do that over a custom thing.

Second, what are the environment rules? I worked for a government agency where we weren't allowed to use Azure, AWS, Launch Darkly, or any third-party system that wasn't vetted. Thus, we had to make a lot of our own solutions.

And the last thing is what trade-offs do you want to live with. Do you want to be tied to Azure, Launch Darkly or something else? Maybe an open source, self-hosted, or self-built solution would be better if you are trying to limit the amount of outside dependencies.

There are so many options out there, and there isn't really a single perfect solution. Each project, and scenario requires thought, planning, and design.