I came across this sentence:
Stripping the sentence to basic sentence structure:
How can that be grammatically correct?
As "広める" is transitive with an obvious object, there must be an actor as the subject? I don't see one. You can sort of hide the actor using passive voice. This seems grammatically correct to me:
Or, isn't the intransitive verb also an option:
In English, the given sentence sounds to me like:
??? is widening the appeal of the dance.
But, who is widening the appeal? Don't you have to say:
The appeal of the dance is widening.