There is of course Adobe Illustrator and that type of curve. I also had to learn a different type of curve editing and drawing using Animation:Master (3D). Then I learned the curves in Anime Studio, and now I'm learning the "curve" editing of 3D shapes in Lightwave. They are all different. Oh and then add in animation channel editing and motion curves. So you have Premiere, After Effects, Anime Studio, Lightwave, etc etc. They all "animate" and have key frames but it's different in each application.
Yes, I agree it can be very frustrating to constantly learn a new way to do the same thing but there is no easy way around it. At least now it's easier to find answers and solutions with the internet. When I first started with this stuff I would have KILLED for all the free resources available on the internet today. There was no google or easy to find answers when I first started learning applications. I had to buy these huge thick books, read manuals and use trial and error.

One trick I learned with Anime Studio is to do as much as possible IN Anime Studio. If I don't absolutely have to use something else to get the effect I need, I do it in ASP.