I do not, myself, know why this is the case. I can come up with several plausible reasons; for example, you're basically coming up with an alternate input device for your computer piggybacked onto something that's already there. Additionally these programs basically are the computer if you're blind; you develop a lot of experience with them quickly because the alternative is not using it at all. And some amount of it is probably cultural/historical, we make it hard because it's always been hard. Truly, I don't know, and I don't know anyone who does.