Actually, in WoW, partying to level up (in the world, not in instances) can and will slow you down. In most areas, the xp gains have been tweaked such that if you enter an area, do most to all of the quests there, and don't go out of your way to avoid fights or group for anything other than group quests, you should finish up an area in time to move on to the next as the appropriate level.
I usually arrive in Hillsbrad at 20.0-20.5 and leave for Arathi around 29.5-30.5 if I do EVERY quest there except for the two red ones in Alterac. On characters where I've grouped with someone to do the Battle of Hillsbrad quest chain, I've found myself running out of quests at level 27 and needing to go elsewhere to do quests for 3 levels, or grind them out.
Similarly, in most of the LK zones, I'll end up doing Fjord from 68-71, Dragonblight from 71-74, Zul'Drak from 74-77, and Icecrown from 77-80. Doing these solo results in Fjord quest achievement progress completion (or within 2-3 quests of it), Dragonblight achievement complete, ZD achievement complete, and Icecrown quest achievement is around 135-138ish of 140 when I ding 80. This also includes running several dungeons from my trip from 68-80.
Attempts to group for more quests than are recommended (duoed with fiancee from 1-80) have resulted in exhausting zones of quests. Fjord was complete 1/4 of the way into 70 and we had to go to Borean to catch up to 71. Dragonblight was complete at just barely 73 and we had to do a full level in Grizzly Hills, and finally ZD petered out halfway through 76 and we had to hit up the Nesingwary chain in Sholazar to get us to 77 and ready for Icecrown, wherein we hit 140/140 with half a level to go and had to fly over to Storm Peaks (At least she got to get started on Sons of Hodir Rep, I guess).
So while soloing completes quests faster in WoW, the xp loss from the individual mob quests results in lower xp overall and mandates a need to do more quests to make up for it.
Comparatively in FFXI, one almost always had the option of solo, but since 99% of the game's xp income was via "kill mob, repeat", there was very little (if any?) benefit to killing mobs solo. Party play was safer; you usually have someone to raise you if you die as opposed to HPing, you also had a balance of players who, if someone was dying or needed to afk suddenly, there were 5 others to pick up the slack. During the times I was soloing on DRG/BLU in the 60s, I gotta say I had a couple moments where even a few seconds of inattentiveness would have resulted in death, and I had a couple events of suddenly needing to use the bathroom, but being midfight and having to finish up before speeding out of the room, lest I get hit with -2400 XP, thus negating the last couple of chains. Parties at that level are capable of far higher xp/hr than soloers, unless the party is just godawful or competing for an overcrowded camp.
Ideally I think XIV should have some soloability, but not so much that it is possible for someone to easily solo their way to the cap, because the easier it is to solo, the less reason people have to group. And if people have less reason to group and are just going to solo, then the game might as well just be a massively single player online role playing game.
Mikhalia: and FWIW, my posts are 95% helpful, informative, or funny.
Mikhalia: only 5% or less of my posts are utter crap.
Tyapex: 393 posts of utter crap...
Mikhalia: Sounds about right.