Acclimating is important with saltwater due to the different specific gravity of the water along with the alkalinity and calcium. Some people acclimate for fresh to just get them use to temp and some water that fish require a lower ph. If I have a fish that's been in the cooler air long enough to lower the water temp I will float the fish and even sometimes do a drip but it is not always necessary.
I was speaking strictly on fresh water but I would think the ammonia chemistry would be the same or similarly toxic in SW.
Agreed, the SW parameters, and SW fish in general are more of a delicate balance.
As for ph differences on FW fish, it's always better to chance some ph distress (which they recover from quickly) rather than keeping them in water that is immediately going to start burning gills and fins. If you slow-acclimate FW fish using the drip method, or any variation thereof, you might as well urinate right in the bags yourself.
Now, just taking a fish home from your local fish store where they are in the bag for 1/2 hour or so, they obviously wouldn't put off as much waste as being shipped long distance...or sitting on an auction table all day.
Also, I'm not just stating an off the wall opinion of my own making. This knowledge comes from importing and shipping fish all over the country for many years and talking at great length to my suppliers and colleagues in the business. These people do this for a living so it's over many years of experience that these methods have been figured out.
Any exporter, or fish seller that directs a buyer to slow acclimate their FW fish the old fashioned way simply does not understand chemistry.
It's a similar situation with sellers that aren't educated and tells you they ship
all their fish in pure oxygen. Certain types of fish
should never be bagged with pure oxygen. Plecostomus species for example...they can get internal organ damage when shipped in pure oxygen. They will almost always die in a short time.
BTW, I sincerely hope this isn't coming across as argumentative because it is not my intention at all. It's only meant as educational and the passing on of my experience in the mentioned subject.