Ive found that the sparks from my firesteels are hot enough to burn through the paper where they land. If the paper is sitting in a good location it seems to light very quickly for me. With the papers Ive tried so far anyway.
This can be a problem with many tinders, I pick and choose what and how I use different tinders when I need them. Nearly every thing has draw backs, and you can learn to live with them. I like the extra heat that Magnessium gives, but it I mix it with something else, and keep it out of the wind. I'm not saying that I would use it to light every fire.