Especially anime often use the superior .ass subtitle format, which many devices don't support. Sadly Crunchyroll is switching to .srt which has broader support, so it likely won't require burning them in the video (transcoding), which is the only positive thing (still a shame imo).
https://www.reddit.com/r/anime/comments/1nuxuzs/crunchyroll_has_downgraded_their_subtitles