Phasing causes dead feeling in zones

I understand why blizzard phases players. Makes them feel more engulfed in the zone/story, they can clear trash without large respawning times etc. However! Why is it as a Guild you are continually phased from other members you are wanting to help or go out as a big group? We went out to open world pvp and such as a group of 11. Because we wanted credit for kills and such we were not going as a raid. All 3 groups phased from eachother… while in the same zone. As one group finished I would jump to the next group to help them. Group 1 the zone was filled with players… group 2 there was about 6 other players… group 3 there was no one there but my fellow guild members. If people are having the group 3 experience… no wonder they see the game as dead. Everyone is always phased from eachother… instead of seeing 30 some odd people all in the same zone