I also personally question the current trend to do the academic portion online or locally and the dives themselves in a tropical destination. I've seen this presented to non divers but never with the caveats that should go with it. It is often used to "sell" the non diver but they wind up practical learning in conditions that do not reflect their home locale.
Where I instruct in Colorado roughly 80% of the students who do their academic and pool instruction locally finish up in a tropical resort. We have only a couple of local sites that are diveable, and just about none of them are dived in the winter. IN the winter, the best options require a 7 hour drive, one of them to a thermal pool in Utah that is like a 94 degree hot tub. I strongly suspect that 90% of the people who complete their certification locally will never dive locally in their lives. Only a hearty few do so. I would guess that 90% of the students I have taught intend to do 100% of their future dives in warm water resorts.
The fact that you are only prepared for the kind of diving in which you are certified is a part of the instructional content, and it is part of the testing. Students are required to demonstrate that they know that.
Finally, as I have said before, when we are teaching students in the academic and pool portions of the class, we may have some going tropical and some going local. We prepare all of them the same way. Everyone leaves the pool with the same training. There is virtually no adjustment needed for the ones who dive locally. If a tropically-trained diver decides to dive locally, it is no big deal to make the adjustment. As I also said earlier, ALL of my certification training--academic through open water--was done in the tropics. When I decided to dive locally, I wore a thicker wet suit and more weight. It was not exactly a life-altering change.