Warning I probably don't know what the hell I'm talking about. However my gut instinct is that self similarity mean shorter code (dna) shorter dna (protein chains) take less energy to copy thus gives you a survival advantage (often survival for plants means getting set up and leaves out fast). An experiment was done a while back where they took a bacterium and 'unrolled the code' of the dna (seems there are deduplication routines in nature). When the result was grown in a lab it behaved just like the original but didnt grow as large.