You normally find ema at Shinto shrines in Japan. People write their prayers and wishes on them, hang them at the shrine, probably nobody reads them, and eventually they are burned. If they weren’t aesthetically pleasing (and a possible source of the placebo effect) they would be completely pointless.
Not so with these Baseball Ema which you can find at the home of the Fukuoka Softbank Hawks (福岡ソフトバンクホークス). These are for fans to write notes to specific players. I suppose the players eventually get to read them. Kind of fun and very Japanese.