There is no reason why non-keyboard characters should be blocked. Apart from essentially banning certain languages (Chinese, Japanese, Greek, Vietnamese, Korean- if those languages are going to be banned, you might as well ban Spanish, German, French, etc), it becomes harder to express stuff ("Obsidian Rank is 139.99£", "It's coming out soon™", "¿Cómo escribir en global?"). So why are they blocked anyways? "They are blocked to prevent spamming"- this will not help to deter spamming in any way. No special characters? No problem! Just spam keyboard characters!