This is not true. Blitzbasic did the same way before. Conitec could have learned from their failures.
They created an object oriented modern language called "BlitzMax" for their game-engine and it failed. Why should a user learn a complex new island language if there are others like C#, Java, Delphi or C++ available?

Let us think about it more deeply. What is our goal? We want to render nice contents at the screen added with good music, sounds and effects. So what will our customer see? Graphics. What else? Customer will listen to music, sound and will try to control through keyboard, mouse or gamepad.

So what is important for the final result? Rendering, sound playing, input of control data. The programming language is only a develeper tool. It could be exchanged with everything else like C#, LUA or Angelscript.
The best compiler with super optimized code will not help you to make a competetive product if your renderer is weak.