Interesting that you pick GOG and Itch as examples, because I have all my gemes from these platforms available Through Lutris in a central interface. And it works well because Lutris can, provided my login info, just download and install the games without needing any extra services.

I made that point short to be pithy, but what I actually take issue with in there being so many streaming services is that:

• Upfront transparency for what shows and movies are actually there, let alone in what state, is often incredibly limited. This isn't inherent to there being multiple services, but when I haven't found one whose experience isn't profoundly shitty, I'm counting it against them.
• Even if you accurately assess which subscriptions you need at first, that can collapse at any time because shows are treated as playing cards, and you often need to put ongoing effort beyond just paying money into maintaining that list. (I often watch shows over months or years instead of binging them, and this is super shitty under a streaming service.)
• Even if you have all those subscriptions and maintain them well, there's no place to centrally view their content, something which cable TV – for what a piece of shit it was – shockingly made easier than streaming. If I purchase half my games from Steam and half from GOG, I can still access what I buy from a shared location: my desktop. If I purchase a bunch of discs from multiple different vendors, it's all centralized on my DVD rack. The UI is consistent (and even slightly quicker to access). This isn't massive, but it's still objectively a point against them.
• Unlike the PC gaming landscape where games are often available across multiple stores, streaming services are becoming increasingly exclusivity-focused, and this happens because there's such an oligopoly in the TV and film industry, and basically every member of that oligopoly now runs a streaming service.

I don't think the point should be that there should be one streaming service to rule them all, but that in their current state, they represent an objectively substantial downgrade to piracy even taking away costs.

Nah. We need legal protection to separate content creators and distributiors. Creator's license content. Laws could mandate all distributors get access to the same pricing. Then you pick the distribution platform you enjoy.

Creator's compete for views with quality content.

Distributors compete for users with features and curation.

No exclusive rights. No studio running a streaming platform. No streaming platform starting up studios. None of this anticompetitive lock-in.