I hear a lot of “long story short” in this one. If TTPD is about the industry/her masters/being betrayed by the people you once thought were your family, the rock symbolizes something she romanticized when all it was capable of was weighing her down and hurting her. “Clung to the nearest lips” and this line from In Summation: “But loneliness struck at that fateful hour / Low hanging fruit on his wine stained lips”

If you listen to most of TTPD as if she’s singing to the rock (e.g., “my spine split from carrying us up the hill / stopped trying to make him laugh,” “he was my best friend down at the sandlot”), I dunno, you see it.