C# Why shouldn't I ever use coroutines?

Question

One of the comments on this thread: Checking condition and calling continuous method with periods of delay unity, said that:

Never never ever use coroutines. They teach bad habits from the point of view as a c# developer and will lead to a lynching if you take a regular c# job

My question is, why is this? Is this just in Unity or in general? Unity's official virtual reality samples https://www.assetstore.unity3d.com/en/#!/content/51519 use them very heavily (especially the flyer example) instead of Invoke or Invoke Repeating, these sample projects were released recently as well.

Answer 1

This is very much a Unity thing, though the advice is applicable anywhere.

Developers do not expect iterating an IEnumerable to change a program's state. It's not what IEnumerable is intended for and is an inconsistent behavior with all of .NET.

What Unity is doing is using yield return as a pseudo-coroutine, and it's going to cause confusion for any devs unfamiliar with that.

In modern C# we have async/await to accomplish what Unity intended, but Unity was made before that feature was available.