A bunch of the issues you mention aren't issues anymore, thanks to fully featured web applications.

Sure. There's always an exception like graphics editing.

We talk about exceptions a lot. But being in a niche professional can lead to either early or late adoption. A job is a job, and we just use the tools we need.

But for stuff like email, banking, and various document services, the average user's experience is identical:

• Type the product name into Google.
• Register or Sign in.
• Use product.

I do think a good file backup service is one of the big remaining challenges.

Ironically you mentioned two that are I believe are still fully Linux native (Dropbox and Google).

But to your point, people need file backups that just work, and plenty of popular cloud sync services choose not to provide Linux support.