Where was “async” all these days? [closed]

Question

It was started with C# 5's new keyword "async". And now I see this async programming everywhere from Javascript to C++, mostly from Microsoft. And from various discussions I came to know, this is a very useful technique to avoid threading yet keep CPU working while other things are fetched form hard disk or network.

My question is, why such an important topic was ignored all these days? Or it's just a hype from Microsoft?