Of course. However, there are more metrics than HPS and gearscore. Even in just skada/recount itself, there are other tools that are useful to gauge how well a healer is performing. The community at large doesn't recognize or use these metrics, though. Either because they are ignorant of them, or think they are irrelevant for whatever reason. There's no sense in trying to argue or convince someone already set in their ways. I was never successful with this. Where I found my success is when I blew all of the other healers out of the water with the metrics these people understand.
Thankfully, I don't PUG, but not everyone is so fortunate.
A lot of people forget to exclude Judgment of Light from HPS calculations, as it's free healing that usually a holydin will whine and cry about because it's the only way most of them can do any good on the meter.
Guardian Spirit is very powerful too, if you use it properly. If you use it for its healing increase instead of a death prevention, you'll find you'll have it available a LOT (with the glyph). Don't be afraid to stack it with other tank CDs, or on people who need emergency healing.
One could also mention the power of a HPriest's group healing. Which leads me onto the next point;
The rest of your post is on point, but I'm not so sure I agree with this point. Chain Heal may be a smart heal, but you still have control over where Prayer of Healing goes, Prayer of Healing is more powerful if it heals all the targets it hits, and it has greater range. The two are a bit different, and I think different enough for each of them to remain useful. So the comment about "rightly so", I'll disagree with.
That said, however, I would say I also feel that the HPriest wasn't just eclipsed by Resto Shammies. In the 30% buff environment, HPriests are eclipsed by essentially all of the other healers because of how easy it is to heal in the 30% buff environment. Why would you play HPriest when you can effectively play all of the other healers with 1 button for the most part? Lazy people smh... but it makes sense. Outside of this environment though, HPriest competes very VERY well. HPriest is still very useful in a 30% buff environment, it still performs well. The difference is mainly in that you can get away much more easily without having those Prayer of Healing or the versatility of the HPriest when the risk of death is much lower.