Bring back the days of leveling up parties

[Calyanare]

Like others said though, with fates, leves, and now dungeons providing the absolutely off the rails xp that they do, I don't know that you'll ever be able to convince people that sustained per mob xp can top the big instant gratification numbers they see in those things.

The biggest thing that works against XP parties in this game is the respawn rate. In every area I can think of, your chain will be severely limited by the lack of respawns. That, and you need mobs at least 10 levels above your current level to make it worthwhile, and mobs in this game have the same cap as players (you won't find any over level 50). XP party style play should be okay until about level 30ish and then have steeply diminishing returns thereafter. That is, if you can convince anyone to try it in the first place, for the reasons you mentioned.

[Kitru]

That, and you need mobs at least 10 levels above your current level to make it worthwhile

Actually, xp gained from kills is limited based upon your current level compared to the enemy's level such that enemies that are 10 levels higher than you give the same amount of experience as enemies 5 levels above you. The same happens with every single method of xp acquisition in the game (though, because you can't do dungeons or quests above your own level, it really only applies to FATEs and kills).

The way the game is designed, when doing kills for class xp, chocobo xp, or even spiritbonding, you really have to go for quantity rather than quality, a fact that is only made more distinct with the chain bonus. The limiting factors to this are respawn rate, as you already mentioned but also the proximity of high density spawn points. With a large group, your kill speed eclipses the respawn rate of enemies (for those enemies in regions where spawn points are close enough together to make grinding time effective) very quickly, so that you end up either standing around doing nothing for extended periods (which is what happens/happened? with groups camping the mines in North Than) or running to another high density node, assuming there is one. As far as I've seen, the highest number of close proximity (defined as "forming a closed circuit with itself with travel times of less than 10 seconds") high density (6+ enemies within range of a single pull) spawn nodes is 3 (in the back of the various Garlean strongholds). As such, even if your group was wont to move to a new spawn location, you'd either end up spending half of your time running around or having to settle for low density spawn points (e.g. running around the area north of CPS instead of fighting the mines) that provide substantially fewer kills per interval; either way, you're effectively limited on how much xp/min you can gain by just kill grinding.

When I'm kill grinding (choco xp and spiritbonding), I reach equilibrium on the aforementioned 3 close proximity high density spawn nodes with just one other player. The game just doesn't support the open world spawn rates/numbers to make traditional grinding viable. I get the feeling that this was actually an an explicit design decision on the part of the devs insofar as the did not want to have traditional grinding be a particularly effective method of gaining xp and fully intended FATE grinding to be the replacement playstyle for it (it follows a relatively similar model where you're running around with a group in the open world killing stuff together on a relatively constant basis) since it's (nominally) less repetitive and more varied.

Personally, I've never been fond of kill grinding in any game. It gets really boring really quickly, especially when you end up doing the same enemies over and over again so that you're really just doing it all by rote. I've always preferred it when dungeon grinding is the most efficient leveling path, not only because dungeons are, in my eyes, more fun but because they also teach people how to actually play their characters (e.g. proper rotations because they're not simply hiding amongst a slew of other DPS, dodging red zones, target priority and focus targeting on multi-target pulls), which is what the devs did with 2.1.

A reasonable compromise between the desire for old school grinding and the devs' desire to have leveling experiences be more goal/quest/content driven would be for the devs to mix up the guildhests a bit and add more that emulate the traditional grinding mindset (there are a few that do this already but not many) instead of each having a specific new type of mechanic to introduce to players so that those players that want to have non-dungeon "real" group based experiences could hest-grind instead of dungeon-grind.