There’s a reason why some folks object to the GPL: It’s not just a happy fuzzy sharing feeling — it’s a deliberate, somewhat extreme political statement on how software should work.
If you use GPL code in your application’s code—no matter how many layers of wrappers you use—your code is now GPL. If you don’t want to pay that cost, use some other code or write your own. If you use the code anyway without paying the cost, that’s theft. Might also be a well-intentioned misunderstanding, but it’s still theft.
If the Wix app uses any GPL code, they must release the full source code of the app under the GPL — even the “more than 3 million lines of code in the Wix application” not directly related to the WordPress code. That’s how the GPL works. The Wix CEO appears not to understand this.
All arguments about credit or contribution or linking or libraries or open source or github or whatever are irrelevant — your code will be assimilated under the license. The GPL is a viral license and you catch it if you use anything covered by it.
As I understand it, if the WordPress editor code had been under the LGPL (not GPL) and wrapped in a React component — then only that React component would need to be LGPL. But, the WordPress editor code is full-on GPL meaning anything down the line that uses it must also be released as GPL code. Including the React component and any app using the React component.