There are a few things I can see wrong with an online EMT course.
First, and foremost is you get absolutely ZERO practical experience when doing an online class. And when it comes to something technical, is just not a good idea. Sure, you can learn how to size up and put in an OPA, or measure and apply a c-collar but unless you actually get to do it, over and over and get the "fumble :censored::censored::censored::censored:" stage outta the way, then you'll be a mess come state exams, and actual real life calls. Now I'm sure there are set weekends where you go in and do skills stations. And if that is in fact the case then it might not be too bad, or is it...
The second thing that comes to mind when talking about an online EMT class it homework, and questions. It's a tad bit harder to have class discussions, and work questions/problems out when you you are all in front of a screen at different times of the day. During my EMT-A class, one of the things we did a lot of, was have class discussions about random things that we might not all agree on. Like, for instance, why hypersensitivity is a "contraindication" for Epi in an anaphylaxsis call. But as we all talked it out, and the teacher sat there listening to make sure we were on the right track, we all realized it's more of a relative contra, and not an absolute contra.
I guess the third issue I have with an online EMT class is there is no sense of family, in that it's harder to get together, go out to Boston Pizza or where ever and have a study session.
Those are just my opinions, and I'm definitely way more of a hands on, talk it out in a group learner than a read it in an assignment and have learned it!