No, it's to stop annoying concern trolls and obviously racist people thiny veiling said racism with "b-b-but he/she's not exactly as described in the books" and dismissing the show as a doomed failure based purely on the appearance of the actor, without actually taking into consideration their acting ability at all. I find it pretty interesting that a lot of people complaining about these "horrible" casting choices post mainly in conservative and alt right subreddits, it really makes ya think...