To some extent, usability. But since the target audience was always technical (although gullible) people, the incentive to make it useful beyond coin purchases

To some extent, usability. But since the target audience was always technical (although gullible) people, the incentive to make it useful beyond coin purchases never manifested. But moreso: scalability. The blockchains that are worth anything don’t scale to the level of total worldwide transactions per second. I’ve heard “But Lightning!” — sure, so before I can send any money, I have to find a fellow to relay my transactions against.