“Hello! It’s 2019. You expect me to write a thank-you note? I haven’t handwritten anything since grade school. Certainly it would be illegible. Are they texted these days?” (That’s our creative license. Thankfully, no one has stated it quite that way.)
The answer is, yes, graduate school applicants should still utilize thank-you notes. A well-written note can only advance your candidacy. Furthermore, it’s never going to arrive before the interview evaluation is completed. However, should you later find yourself waitlisted, that note will already be in your file. Perhaps most importantly, it will clearly signal a sincere and enduring interest in that graduate school program.