@potato cod and the precise premise of your OP.
Yes, everywhere one dives has been degraded, since before we’ve been diving it.
Most of us had a first recreational look in the early 1970’s. Has is changed for the worse? Yes, absolutely, universally. I started in the Caribbean, and after repeat visits to specific dive locations in 1970, 80 and 90, no I won’t be going back to the ones that were the “must dive” list in 1970. I’m skipping the ones that were hot in 1980 and 1990, as well.
In the Caribbean, the Pickens are getting pretty thin for my past comparatives. Internationally? There are always new rocks to plunder.
Many divers I listen to on SI decry the “lack of fish”. Those are the divers who are real busy diving or checking out their depth gauges. I’m still seeing lots of fish. I’m not seeing as much/many as I used to see, but those speaking up about lack of fish are too young to have my base of reference. Maybe it’s a hip statement to make before someone else does.
Same for coral reef health reference this time versus whatever last glimpse you had. It doesn’t really work that way. Talk to me about watching it often and over a ten year period. Your comment about coral bleaching on this trip equates to background static on my end. I’ve seen so much of the incidences and comparative alarm, bzzzzzz.
It was not on topic, but the earlier post and suggestion about over-paying for a dive Trip by being convinced you’re on a scientific endeavor, stuff like that still amazes me that they can con people into that.
So, yes- there are places I no longer can be dragged to go diving. I could state the names, but it would not be fair or relevant, as to those on a first warm-water-pretty-fish (WWPF) dive, they will post the “it was just the bestest dive operation ever”! They will be 5* for sure on Twit Advisor and Cruise Critic.
Experiential bases expand, becoming jaded is a hazard.