Knowing how slow (good quality but slow) lame is on a full edged computer this option should be turned off by default and should need to be manually enabled, as otherwise all unexp. people installing on a slug would lock up that slug CPU wise.
Even the fastest synologies will cought out hard on any attempt to encode mp3’s no matter how low you set quality.
So as nice as it is as a feature its limited to full computers with their massive energy consumption.