I guess that's all you can do is be thoughtful in your decisions. Humans will always be detrimental to their environmentsl, but as a personal consumer I try to do it in the most efficient way.

In the grand scheme of things I don't think my grandkids will blame me and my fish tank for destroying the oceans, so I don't think it's a huge impact and the more we push for sustainable caught fish/corals or even better bred fish/corals, properly mined rock, more power efficient equipment the less impact we will have. Also frag swaps and buying locally have got to be more utilized, why don't we have a Canadian MACNA!!!

On the rock topic, I think that there is less and less of the 'live rock" taken out of the wild so to speak. We now have tons of other options available, aquacultured rock, man made rock etc. As hobbyists become more aware and educated wild rock will probably become a thing of the past in the hobby.
I myself do not have wild live rock in my tank.

My biggest pet peeve of the industry as a whole is the insistence of lfs's to keep getting in known hard to keep alive fish, moorish idols, orange spotted file fish etc. I don't mind if an expert reefer has done their research and wants to special order something, but getting in 10 or more in a shipment just to sell something "rare" is not right.

I still have all real rock in my tank :)

Keep in mind, often the LFS simply gets what is sent. I've seen stuff come in where the LFS is p'ed because it won't live. They order 50 fish, 30 are available on day of shipping, the supplier fills the rest of the box with whatever they have on hand.

Back to the original question..

Do we help.?

I can't think of one possible reason how anyone in this hobby can begin to say 'they help'. Short of returning all the inhabitants of their tank back to a SUITABLE location or origin with the remote chance it will survive and reproduce Which its self is a ridiculous scenario ......You... Don't .... Help.

Do we hinder..

Ummm ya we do. There is zero benefit to reefs to remove any inhabitants for the hobby trade. ...None, zippo, nada.

In my eyes it is black and white... I'm not a granola eat'n tree hug' earth muffin. I do this for my own pleasure end of story.... For people who have taken steps to populate their tanks with tank raised this, fragged that, farmed blah balh blah, good for you.. But believe me any neub that is inspired by your tank and decides to take the plunge into this hobby won't have the relationships built up to be able to do the same.... End result off to the LFS they go....

And I can't really come to any different conclusion.

Without the hobby there probably wouldn't be so many scientists working on captive breeding projects because they'd be so far behind in husbandry knowledge and equipment.

That's all I got.

Without the hobby demand, there would be no need for captive breeding..

Um, no. They are researching captive breeding for the end result of being able to re-establish wild populations. Collection for aquariums isn't nearly the only reason they would want to captive breed fish. I'm not just talking about aquarium fish.

Where did the wild populations go? Oh, right :)

Well, that explains it... Kind of hard to explain colours to people that only see black and white...