The arguments for using #camelCase(Capitalizing the first letter of each word in a #hashtag): (Or #PascalCase)
It's inclusive for people using assistive technology
It makes the hashtag easier to parse for everyone - especially people learning a language, and those with learning disabilities.
The primary argument against it is simply that hashtags have traditionally been all lowercase.
Let's make accessibility the norm rather than the exception. #Accessibility Matters