Get off my chocobo to raise someone? Absolutely not. (I can't...I have no jobs with Raise ^^)
Help someone who has called for help? Frequently. I'm finding it's rather difficult these days though...it's as if the populace has, as a rule, forgotten that if you want me to kill the mob that you have engaged and are losing to, you have to actually use the call for help command. Usually all I see are shouts for help in my log with no coordinates, much less a compass marker to guide me to the trouble spot.
As far as helping a party in an exp area that I'm also leveling in...that's not a yes or no answer. Generally speaking, it's always nice to lend a hand, especially in higher level crowded zones. The tension between groups over who is camped where and getting what mobs eases a lot when you show a little comraderie. This isn't so in lower level zones like Yhutunga, where I've had more than one party turn around and say or do stupid things to my group after we have helped them out of a sticky situation.
Overall, it's important to remember the old saying, "Once bitten, twice shy." People who do not stop to raise a random person, or rush to the aid of someone who calls for help are not necessarily selfish players. It's entirely possible they've just been burned one too many times by dim-witted idiots. While I wouldn't say that should be a reason for calous disregard for fellow players, I know I certainly don't exactly wander Vana'diel looking for hapless adventurers in over their heads.
In fact, the last nasty encounter I had with a player came as I was running through the highlands towards N. Gustaberg. I ran past someone who was fighting a couple of lizards and didn't think much of it, having already passed by a handful of people train farming sheep in Mary's spawn area. I had gotten just beyond bow range when I saw a message that this person was defeated by one of the lizards...he was soloing for exp and got a link. I felt a bit of guilt, but he was engaged on one lizard...if he wanted help, he should have typed /help or even "help pls".
So I felt kinda bad, but it hardly ruined my day. As I'm almost to the zone, the person runs past me heading in the opposite direction...they had obviously set their homepoint in N. Gustaberg and released. They /slap'd me on the way by and proceeded to send me nasty tells because I didn't help them. I explained that I was sorry, and didn't know he needed help, but the nastiness continued. I tried to explain that if he wanted help he should go about asking for it appropriately, yet he continued to accuse me of being a selfish "hi level jackass".
I've happily and naively crisscrossed the Dunes of Valkurm to help a random person get the Magickked Skull for sub-job quest. The person never spoke as I ran around scanning, and when I finally found a ghoul, it dropped skull right away. I was kind of proud of myself, but the person I was helping wasn't even paying attention...I had to do a <call> to get them to pay attention and lot on the skull so I could disband and go on my way. The gratitude they showed me for helping them overcome such an odious obstacle?
"oh, thanks" No smilie, no "^^", not even a ! for my trouble.
Sure I'm willing to help, though I'd have to suggest based on my experience that someone who doesn't drop what they're doing to assist someone else isn't necessarily lacking in "solidity" as a player.