The job system is actually a good example of what an "uncapped" system looks like since people are free to cap jobs as they see fit without limitation. For any given person though there's actually very little benefit from capping everything though so most people don't bother, they just cap the things that interest them. But if someone is interested in capping everything, they are free to do so.
Uncapping HP, MP, combat skills, whatever wouldn't really create much tangible advantage for players who cap everything over someone who did not choose to do so since stats don't really apply to all jobs. my INT, MND, CHR merits are doing virtually nothing for my melee jobs except in rare cases, my STR, DEX, AGI merits aren't really doing much for my mage jobs when I'm playing those. Having capped MP merits doesn't help me at all when I'm playing DNC.
Debate is academic though because they're not going to lift the cap completely because they don't understand economic rationality.
