This is the problem with any generalised "anything you do that might one day compete with the company" criterion. Even if an employer only claims work that an employee does on their own time that relates to any current company activities, there is still the need for an employee to know about the other project, which is hardly likely in a huge company with 100,000s of staff worldwide.
I think the standard should be that things the employee does that are directly related to their own employment are what is covered. It's fair enough for an employer to claim ideas directly related to the project you're being paid to work on, and/or to say that you can't compete in closely related fields to what you're doing for your employer. However, that's a very different thing to counting effectively the entire world of software development, if anything that any part of a large software company does or ever might do could be claimed.
