I think that was clearly stated in the quote I included in my last reply. Let me reword that: a) it interrupts screen readers, which are something some people rely on frequently. The reason is accessibility. b) It makes it harder for dyslexic people to read the text.
I see no good arguments pro placing hashtags in-line. If you've got one, please tell me. The above mentioned are just two contra arguments and there are others that may be less important.