I think the argument comes in that, this actually doesn't apply to those who don't have said system. Imagine instead it's a stamp that only applies differences if the recipient also subscribes to said stamp service. To everyone else, it's just a regular letter. I can easily go use a different service of the same type to achieve the same benefits.

And yeah, they do use their system to benefit their shareholders, which is what businesses do with their proprietary services.

Im not arguing for this by any means, just trying to play devils advocate as for why Apple would want to maintain control over it and why I think it's odd that the government wants to get involved. I feel like companies like amazon do more impractical shit to maintain control over the market, but bubble colors just aren't anywhere near the top of the list for things I think politicians need to spend time talking about.

I wouldn't be upset if they forced apples hand, though, others have pointed out that it would even the competive market for other manufacturers

iMessage is not a stamp in this analogy - it is a whole separate post office and infrastructure, including staff and policies.

You’re mischaracterising the argument.