What is LRC?

The lyrics format, from the days of ripping CDs. One timestamp per line and no end times at all, because a music player only needs to know when to highlight the next line. That missing end time is the thing that complicates every conversion out of it.

What is ASS?

Advanced SubStation Alpha, the format serious subtitling actually uses. Fonts, colours, positioning, rotation, karaoke timing - anything you've seen a fansub do, it was doing it here. Converting to SRT throws all of that away and keeps the words.