The Cap is a stupid, pointless system that does not promote tactics or grouping up. If you had a full party of 8 R40's to get max SP you go kill Raptors but they would die in seconds you probably wouldn't even need a mage to cure, and they are pretty much the best Grind Mob in the whole game.
I understand some people here don't like group grinding and that is fine, SE are catering to you with other forms of content like the Guildleve system. For me though I like to group up and grind mobs with people and this system does not cater to me or the other people like me. It provides no challenge, no risk and no incentive to play your role properly. You can say well go fight something tougher but what is the point if there is no reward for it, the only reward is slower SP.
When you do Leves if at 3 Stars the Mobs Rank is 10 higher than you why would you do it on 5 Star when the SP will be the same. The only thing that will happen is it will take longer but the reward is still the same so it's pointless.
There are three ways I would like this tackled:
1: Raise the Cap to at least 20 Ranks above your own.
2: Make a mob the same rank as you an actual even match so they are a challenge, then something 10 Ranks higher would need an entire party to take down. Obviously adjustments to SP would need to be made.
3: Lower the ranks of all mobs by 8/9 but keep their stats and SP the same, this would have a similar effect to number 2 but might be easier to implement.
As well as these adjustments to the Cap, they need to make adjustments to Mobs distribution and Respawn times to make Grind Parties viable.