Where I work, software purchasing is outsourced to a third-party company. I can appreciate the value this provides.
And part of the reason why I hate the trend of turning everything into services is that regular (middle-class and below) people don't get to outsource the increasing amount of relationships they have to enter into.
I too find it exhausting to manage all my subscriptions, communications, and such. I wish I could just hit "cancel all" and restart them as I needed them.
It really feels like there should be a well-funded startup attempting to tackle this problem by now.
A central service where you can easily manage many subscriptions, with integrations into other websites. There are a lot things I would pay for if I didn't have to go through the process of creating and managing yet another account. If it was just a one-click add/remove.
News websites come to mind. I would also use a "buy access to this article for 50 cents" feature. It just has to be frictionless.
The major players might not want to give up the money from people buying subscriptions and not using them much or forgetting to cancel them, but that seems like a lunch ready to be eaten.
Justifying the need for it, go though the paper work, estimate costs etc. VS just adding a new line item in an existing bill.