> Some examples of search results from Facebook / Discord / Twitter ? And on the same level as other pages, not in some separate field ?

What does a "separate field" have to do with anything? Now a site is or isn't part of the web based on how Google formats them in their search listings? These sites serve media meta-tags specifically so that Google will index them, they depend on SEO. Find someone famous with a Twitter or Facebook presence and search their username and whatever public information they have, including excerpts of recent posts, will probably show up.

>Browsers can do a lot of things these days that are not part of the Web : display pdfs, ftp folders, rtsp streams...

But your assertion was that websites which use javascript to render text, applets or flash weren't part of the web, but somehow just part of "the internet," despite everything on the web also being on the internet.

We seem to fundamentally disagree on what the web is - it seems like your definition is more aesthetic than technical, and that you believe only static HTML pages should be considered part of the web.

But according to at least the w3C's Help and FAQ page[0], the difference between the internet and the web is:

    The Web, on the other hand, is defined in W3C's 
    Architecture of the World Wide Web, Volume I as 
    follows: "The World Wide Web (WWW, or simply Web) 
    is an information space in which the items of interest, 
    referred to as resources, are identified by global 
    identifiers called Uniform Resource Identifiers (URI)." 

And in the Architecture of the World Wide Web[1] page we see a lot of information about URIs, HTTP requests, XML etc.

But nothing supporting the claim that "If your "web"site can execute arbitrary code, and/or violates HTML guidelines (...) then it might be part of the Internet, but it's certainly not part of the World Wide Web!"

I mean, the <SCRIPT> and <APPLET> tags were added in HTML 3.2, and the reason <SCRIPT> had a "type" attribute was that the intent was for browsers to support multiple languages. It seems kind of absurd to argue that somehow embedded code was never intended to be a part of the world wide web, when it was considered so early.

No one who was actually involved in the architecture of the web appears to have ever had such a rigid definition of it, or such a limited vision of what it should or shouldn't be. Here's a thread from the www mailing list from 1995 about web scripting languages[2], I don't see anyone arguing that the concept is fundamentally hostile or antithetical to the web or HTML. Rather, as hackers tend to do, they discuss the ramifications and pros and cons and possible implementation.

You may not like that this is the web, you may not agree that this should be the web, but this is the web.

[0]https://www.w3.org/Help/#webinternet

[1]https://www.w3.org/TR/webarch/

[2]https://lists.w3.org/Archives/Public/www-talk/msg00099.html