I wouldn't say they didn't get jack shit. All but one got something I can name from memory.

Rarity, for example, had a personal audience with Celestia and her own suite within the palace to say for a few days, for one example. Pinkie Pie was allowed to cater an event for Celestia, and Rainbow Dash was awarded 'Flyer of the Year' or something by the deity. Fluttershy was granted something that appears to be from the other deity, Luna, during her little bat phase. Applejack, I have no idea what she has gotten ever since she met Twilight.

Furthermore, they all have big stained glass pieces of their triumphs and themselves, basically recorded in history, for when they die their legacies and stories will carry on. That's gotta be somethin', right?

TL;DR They're Heroes of Equestria, they practically earned their royalty.

Eh if it was that straight forward then MLP would have been a boring as hell show to watch and never would have gotten off the ground. If anything each of the 5 taught Twilight their respective element of friendship which means the respective ANGLE on how they viewed a friendship. Given that when each of these single elements of approaching angles are brought together the result you get is friendship (both literally and figuratively) you can say that as a team these 5 taught Sparkle but its a really big stretch to say that each of them knew WHOLEY what friendship was all along………..uuuuuuh no……………..that's NOT why we watched the show. We watched the show to see 6 ponies grow and learn from each other each seeing friendship from a different angle with the help of the others.