well since i'm in Libra too, i'll throw in some comments on that

general view
1. some people arent able to get the spd desired
2. most people have close friends that able to provide chars for bursting
3. not all ppl understand that horse IS NOT NECESSARY

personal view

i dont really like the idea of bursting with random people (even if they know what they supposed to do) because its like pointing a dagger to yourself.....why would you burst with people that might be your enemy later on ? indeed...

even in my guild its kinda hard finding a bursting team at times (well dont ask bout this part, its boils my blood even to think about it)

i rarely burst tho, only when there's 2x exp day...on the other day i level by remote or just helpin out ppl in the guild~