your example of the blind spot is quite elegant and convincing. I think it's partly so convincing because there's a large fossil record and diverse phylogenetic tree, with many gaps covered. conversely, we're missing direct evidence for the pre-LUCA era, and what we have is bottlenecked. this makes me more skeptical.
for instance, I've seen arguments that the codon mapping, and even the particular set of protein- coding amino acids, that we ended up with was arbitrary, but I've also read papers arguing that the amino acids include a sort of spanning set of different structural scaffolds with different polarity that happen to mesh well with DNA, and that the particular choices of codons were influenced by how the RNA t-acyl transferases arose, etc.
so, I'm still unconvinced, but I find this area fascinating to read about.
for instance, I've seen arguments that the codon mapping, and even the particular set of protein- coding amino acids, that we ended up with was arbitrary, but I've also read papers arguing that the amino acids include a sort of spanning set of different structural scaffolds with different polarity that happen to mesh well with DNA, and that the particular choices of codons were influenced by how the RNA t-acyl transferases arose, etc.
so, I'm still unconvinced, but I find this area fascinating to read about.