I get what you're saying but I think there's room to do both, having lower ilvl sync and time-gate reward tiers. I think it would be really neat in high level content if the devs calculated the perfect run added 30s and made that time-gate drop enough special rewards for every party member to get one, that could be eight mounts, eight music rolls, eight minions, eight materials or any combination of as a reward for doing a perfect run, then step down from that to a standard set of drops at a higher rate, so on and so forth until a truly abysmal run is practically a participation trophy.