You
can also make safe and reliable applications in C++, or fast applications in Python, or readable code in 1990's Perl - it's just very difficult, because those languages lend themselves very poorly to those things, and that's why good developers avoid using those languages when those traits are needed.
Heck, you can make fast code in Python by embedding a DSL and writing a native-code compiler for it. Turing completeness means that everything is possible, which means that "possible" isn't interesting - practical is.
Judging by how few fast webtech applications there are, it seems like making them is not very practical.