The idea is rather that someone with a large FLAC library, who has already transcoded some of it to MP3 for listening on a portable player, has little interest in transcoding their FLAC files to Vorbis again.
The battery life of an MP3 player, even with a ten-year-old battery, is still more than ten hours of continuous playback regardless of the format, which is more than enough.
The real limiting factor is the maximum size supported by microSD cards. If the player wasn't limited to 64GB, I wouldn't even bother transcoding.
The real limiting factor is the maximum size supported by microSD cards. If the player wasn't limited to 64GB, I wouldn't even bother transcoding.