I don't see the purpose of the star-limit. Why is there one? And, if possible, can we have unlimited stars? We do after all, have some star-happy users.
Stars are designed, like upvotes and close votes, in that, they should be used sparingly to determine the worth of questions, or in this case, chat posts.
By limiting stars you can avoid situations like this.
With unlimited stars, you could potentially star everything and then the whole idea of starring to highlight interesting content would become pointless.