It the only reason why intelligent, civilization building species developed on land and not on the ocean floor the lack of energy to drive necessary ecological complexity and amount of biomass it subsists on? (Land gets up to 1kW/m2 from the sun, and most ocean is dark.)
Our chemistry relies on numerous bonds that break outside of a relatively narrow temperature range. But life on earth all depends on the same first cell, so there was never any other option. No other evolvable self replicator to choose from!