The first 3 points are basically the same point: not all Linux systems use the same desktop software. There's a part about adobe that really belongs in point 5.
On the 4th point, everything has a learning curve. When you want to use something new, you've got to learn how to use it. I've used different systems over the years and unix-like systems are by far the easiest to use once you get the hang of things.
On the 5th point, it basically comes down to network effects. This can be a real practical "right now" problem for people, but if you want to use something you think is better this point aside, you should so as to negate it. It takes people needing things for other people to decide to do them.