Ok, every one else answered now what the reasons are, why this is done.
But as it is tagged as Asperger and this behavior challenged me quite some time, I would like to give you advice here, how to better identify and handle that behavior.
I once had a friend from Hungary, and it seemed to me like being a thing of culture, he always was telling me what I "have to do", what I "must see" and what I "will enjoy", but instead of talking about the topics he came up with, we ended in a discussion all the time, of how he dares to try to tell me how to live my life.
I wasn't realizing that thats not what he ever wanted to say by that.
So as Aspie, I figured some time ago out — as I mentioned already in the comments — what makes me react so sensible on this kind of phrases is the fact that the statements are absolute, I felt besieged as it didn't leave any option for my personal impression, as I simply got dictated how it will be. I was worried how to react if I disagree, would I call him a liar if I tell him afterwards that I didn't enjoy it? Would he maybe see me as minor being, as I don't fit into his view of what people should be like? And many other thoughts had been the unconscious worries, his phrasing generated for me.
Well I can't tell for everyone on this planet, but for the majority this simple rule works out for me:
Whenever someone approaches you in a way, telling you what you are required to do/behave like, because they do and enjoy it you can safely assume they just mean it in the way, described by all the other answers on this post. Just start thinking critically about it, when that person telling you about it, is for no apparent reason not doing it them self.