Improvement in pure functions specification

[Timon Gehr via Digitalmars-d]

On 20.12.2016 23:49, Andrei Alexandrescu wrote:
> https://github.com/dlang/dlang.org/pull/1528 -- Andrei

Good, except:

"$(P `pure` functions returning `void` will be always called even if it 
is strongly `pure`. The implementation must assume the function does 
something outside the confines of the type system and is therefore not 
allowed to elide the call, even if it appears to have no possible effect.)"

I think this makes no sense. What is the idea behind this paragraph?