为什么代码会积极地阻止尾部调用优化?

The title of the question might be a bit strange, but the thing is that, as far as I know, there is nothing that speaks against tail call optimization at all. However, while browsing open source projects, I already came across a few functions that actively try to stop the compiler from doing a tail call optimization, for example the implementation of The title of the question might be a bit strang