Sounds like you're talking about extensions in general, but for what it's worth- React DevTools doesn't require any super deep permissions¹ and all of the source code is in the open².
¹ https://github.com/bvaughn/react-devtools-experimental/blob/...
² https://github.com/bvaughn/react-devtools-experimental/tree/...
The notion that there's some kind of plan to "weaken the web" there just isn't true. I don't know what you're basing it on. You may not remember this, but when React came out, everybody laughed at it. It was not some kind of asset for Facebook at the time. If we talk about motivation, ours is quite the opposite. We want to empower web developers to create complex UIs, comparable to native apps. We very much want the web to win, or at least to stay relevant.
The only reason React got open sourced and kept being developed in the open was because engineers working on it wanted to share it with the wider web community. They saw something useful in it. Eventually, the industry took note, but it wasn't until a few years later. We believe in open web, and this is why we work on React.
The notion that React is at odds with accessibility is also mistaken. React outputs regular DOM, and common React setups like Create React App include more accessibility checks than you'd get writing HTML by hand. Maybe you're confusing React with something else?
Yes, keeping dynamic JS apps accessible has its own set of challenges (we document some here: https://reactjs.org/docs/accessibility.html), but it's not React that makes it hard. It's the dynamic UI expected by users that makes it hard. If anything, in my experience React makes it easier for teams to adopt better accessibility practices by putting them directly into React components (example: https://ui.reach.tech).
Finally, concerning standards. We've worked and will continue working with standards committees to bring good parts of React into the platform. For example, the "object spread" operator in JavaScript was originally added to JSX, and was championed in TC39 by a React team member. Similarly, we're closely working with standard bodies to improve web app responsiveness. Not just for React, but for all libraries. You can learn more about this work here:
* https://github.com/WICG/is-input-pending
* https://www.youtube.com/watch?v=mDdgfyRB5kg
Happy to address any specific concerns if you have them.
> We very much want the web to win, or at least to stay relevant.
> We believe in open web, and this is why we work on React.
Who is “we” in these sentences, Facebook or the React team? If it’s the React team, then what is Facebook’s motivation? If it’s Facebook, then why on earth would anyone trust it?
The discussion here is motivated by distrust for Facebook, and suspicion about their (your) motives. The specific accusations in the thread above are perhaps a bit out there, but I don’t think it’s addressed well by focusing on the history of React but ignoring the history of Facebook.