The numbers given the essay suggest that Sweden's employment rate is not unusually low, so is your comment really a meaningful basis for making a policy decision?
When it's easy to fire people, it's also easy to fire people for personally motivated reasons, rather than reasons which are good for the company.
For example, the boss might want to fire someone to bring in a family member. Nepotism isn't illegal. But the union contract helps prevent these sorts of (non-business related) firings.
People tend to work better when they aren't worried about being fired for reasons that have little or nothing to do with their job.