Preypacer you realise you are basing your entire argument on the level sync system in FFXI. FFXI was never designed with level sync in mind and it was introduced far to late into it's life for SE to truly balance it with so much they would have to go through.

FFXIV does not have to suffer those same pitfalls if they implement it or at least keep it in mind while designing content and features so that it can be balanced right off the bat. Basically the aim would be to make people want to stay at there higher level for optimal SP/EXP gains but if they did sync to a lower level they could still get decent gains. So for example a Rank 40 fighting in a party synced to R40 could gain 30k per hour but if they synced down to R20 they could only manage 20k per hour. It's still decent to sync to R20 but most would prefer to stay at the higher rank for the better gains.

Sure it would require some hard work and planning on the mob distribution front for SE to pull this off and keep everything balanced but with so little content as the game currently has it would be better to start looking at this stuff now than wait another 6 years and the end up in the same situation as they did with FFXI when it was introduced. Even if they did something simple like adjust SP curves for ranks and increase the SP from mobs as they increased in rank would probably help. So killing a R20 sheep at R20 would give 200SP but killing a R40 sheep at R40 would give 400SP, doing that with adjusted level curves would make it more desirable to stay at your correct level as opposed to syncing down 20 levels.