People this has to stop!

Initially they were overwriting on the test server:
https://forums.station.sony.com/dcuo/index.php?posts/1964018/

A change in the patch notes indicates a Healer would not overwrite the Damage from a Damager and a Damager would not overwrite a Heal from a Healer:
https://forums.station.sony.com/dcu...te-29-and-sons-of-trigon.168053/#post-1978341

That may indicate that it now may work like POT, where only the 1st one down is applied. If that is the case, then No effect is applied from the second person. No Effect applied = Wasted power.
It also does not indicate whether a Healer can overwrite another Healer. Just a Damager can not overwrite a Healer
If it works like this, then there is case for not wanting 2 Celestial Healers in a Raid group.

Testing needs to be performed on individual HOT powers with 2 Celestial Healers.

It's the same as shouting with a CR requirement. You can get worked up, add them all to your ignore list if you want, but you always have the prerogative to start your own group without a requirement.

Clearly, even if you don't agree with it, you can see where they're coming from. They might not want people using their instance as a testing ground. They may already have Celestial powers in their group and don't know what will overwrite/override. They might already be familiar with Celestial, and don't like it (there was a lot of anti-sorcery in T5 for the first few weeks, too).

I'll submit that there might be another reason. I haven't used it, but this notion of a "battle cleric" doesn't fit with our standard group dynamic. It's something I've been thinking about a lot since T5 came out. My main is a nature healer. If I leave my rings on, go full DPS, and put core strength mod in, my restoration is still around 1300. I can still solo heal most content in almost full DPS gear. I've started doing that in FOS3 ... I'm solo healing, coming third or fourth in damage, and third in power-out with supercharge, supply drop, and Accomplice. In some cases, I'm tanking it, too. What does the future hold for a battle cleric?

The future holds plenty for a battle cleric who can range.

I don't recall seeing that Celestial healers needed to get up close and personal with enemies to be effective. Even as a Nature healer (pure healer, though with Core Strength mod), I'm doing plenty of attacking. And that's the way it should be. Last time I got yelled at for attacking was as a T4-geared healer joining a lower-geared Kahndaq group (after we wiped once when they forgot not to stand close to Black Adam when he goes into Zatanna mode).

I think they are Premium players who are just jealous that they can't use Celestial yet.

Last time I checked people forming their own groups were free to choose who they do & don't want, or did I miss the memo?