Not entirely true.

Pretty much all the major browsers implemented websql, which then never made it into a standard as there were no competing implementations [0]. Nice while it lasted.

0: https://en.m.wikipedia.org/wiki/Web_SQL_Database

Can you cite some specific examples?

Do you mean gopher, nntp?

JavaScript is a good example. It wasn't the only web scripting language available, there was JScript and Java Applets and VBScript. JavaScript won and now it's ubiquitous.

And for an example of co-existence of competing languages, see javascript triggering flash/actionscript (e.g. for clipboard access) and vice-versa (e.g. for DOM access).

Both are somewhat dated examples, that is pre-HTML5.

JScript is simply Microsoft's name for its JavaScript implementation. Presumably to avoid Sun's ire.

I agree with your JScript and VBScript answers, but not Java applets.

The entire history of HTML up to and including HTML5. :-)

I was gonna say, i think of all the arguments one can make, this is pretty much the least viable :)

Once the web became mass-market, standards pretty much became a complete mishmash in every area.

XHTML vs HTML?