I sort of agree with the OP, but mainly only up to lvl 40. Once you hit 40, you go to strongholds and in 2 days you can be 50. Other than plvl, there is nothing out there that is compelling me to party or solo up to 40.

Before some of the earliest patches, you could leve link and get a decent amount of exp at lower levels as a party. I am not sure if that is still worth it since i haven't tried it.