Literally marketing nonsense. The Genesis on paper was less powerful than the SNES in pretty much every aspect except for the CPU clock speed, where the SNES had a 2.68 MHz processor versus the Genesis’ 7.67 MHz, so the Genesis had a superior clock speed but clock speed wasn’t something you could directly compare as they were entirely different processors. Marketing took this speed difference as an advantage though and rolled with it.
Sega's advertising positioned the Genesis as the cooler console,[56] and coined the term blast processing, an obscure and unused graphics programming method, to suggest that its processing capabilities were far greater than those of the SNES.
Damien McFerran. "Retroinspection: Mega-CD". Retro Gamer. Vol. 61. London, UK: Imagine Publishing. p. 84. During the run-up to the Western launch of Mega-CD ... [Former Sega of America technical director Scot Bayless] mentioned the fact that you could just 'blast data into the DACs'. [The PR guys] loved the word 'blast' and the next thing I knew 'Blast Processing' was born."