You can use other languages that are not C to do embedding work/hardware drivers/etc, eg: object pascal, which is also a low level language with direct memory access.
I've written hardware drivers using it, for example.

Not him, but I think you are the one that is not really informed about this.

First you keep mixing server and client side code. Client side is exclusively javascript, the other side does not matter, you can make a web app backend in any language.
And the web is indeed a runtime enviroment, as long as you are only talking about the client side,
You can consider web/browser just another compiler target/platform. And use Delphi or C++ or other "traditional" languages to develop to the web, using a compiler that targets JS as output.
There's nothing stopping you from seeing the browser as just another "platform". Indeed, with things like asm.js, you can treat it as just another cpu architecture. And with HTML5, most features that you need to make almost any kind of app are exposed (AFAIK, the main feature missing is proper sockets support)

No one forces you to use javascript, that's why things like Coffeescript exist. And for example with LLVM you can target browsers with any language that has LLVM support.
Note that I'm not advocating that it is the best solution, but in some special cases, like when you want to port an existing desktop game to the browsers, it is the best solution, like the guys from Unreal did with their engine, and the guys from Unity have already working on letting you use C# to develop browser games.

Also, no one stops you from using frameworks that abstract the UI stuff, so that you could perfectly make an app that runs on desktop and on the browsers, and works and looks the same, using any language (in theory of course, as long as tools exist). That's exactly what I'm doing now, I'm developing a 3d modelling app, using Delphi, and in future I plan to offer a demo version in the browser, so that people can try it without installing. And I'll just treat it as another platform to compile to, nothing in my app code will change.

So he is right, as long as Turbo Pascal was updated in 2014, you could probably use it to make web apps.
Targeting browsers with traditional languages that have small runtimes it is really not that difficult. Maybe you would find some framework or library that would not be compatible, but even in the web, I've found many frameworks that have trouble supporting all browsers, as some times they have features that don't behave the same or not exist in some browsers (this was worse in the past though, even IE is starting to behave way better in the latest versions).

And again, I'm not saying which approach is best or whatever, that really depends on the kind of app someone intends to develop, proficiency with different languages/tools, etc.

In fact, the games created by Mika Mobile make use of a 3rd party engine, Unity 3D. So many people around here talking about shitty ports, when none of his games were written in Objective-C and then later ported to Java, but they were rather written in C# and just recompiled to Android (albeit with some minor modifications, as handling different resolutions etc). The problem with Android is well, lots of problems, piracy is rampant, and there indeed lots of problems with hardware drivers (even using a 3rd party is not enough, and with so many devices, there are lots of bugs to find)