That said, there is a factor for people that if something is out of sight, it's out of mind. Being involved with the ecosystem really is the only way I've seen protection of it happen, people just tend not to try to protect something they aren't engaged with. I'd rather everyone dove, even if that brought traffic to certain sites up, because I think they'd make the macro changes we need to make to preserve things while accepting the micro change in boat fuel use or reef traffic, or whatever risks you're thinking of. Seeing a fish trying to escape from a plastic bag is a sobering experience, you only need to see it once.
There's plenty of nature reserves that have tourism limitations for the very reason that high traffic has negative effects.
The best thing for the reefs in Thailand was Covid (ie, the absence of people)
1) Boat's anchor doing physical damage, which is why popular dive spots have mooring buoys.
2) Many popular sun screen lotions are really bad for coral.
3) Physically touching the coral can do damage, even if gently.
Are there any other factors of which I am unaware?
My primary function for diving is to protect the kelp forest where I usually dive by removing sea urchins, whose population has exploded, killing the kelp. This is done in conjunction with the department of fish and wildlife.
Any scuba diver knows never to touch the coral, the ground, or anything like that. Fairly simple
It seems that the Sea Star Wasting Syndrome, which killed off most sea stars along the western North American coastline, might have been exacerbated by unusually warm water in 2014-2016 which stressed those animals. The death of those predators caused the purple sea urchin population to explode and they ate up most of the kelp. So it's all connected. (I'm sure your aware of this, just providing a little more context for others.)
The best way not to effect nature is to not interact with it.
Obviously that's not 100% possible nor pleasurable, but for more sensitive systems, it's more necessary.
Even then, you could see the difference in the John Pennekamp State Park reefs from when I first snorkeled them in the 1970's.
What active contributions are you making to the wellbeing of our reefs?