Ask HN: Why did smartphones become a single point of failure?

i can't log in to any of my banks without my phone. Most of the systems in my workplace also require phone app authentication. I can't do any of those things with just a PC or laptop. Smartphones being the smallest and portable are surely the most lost and stolen. If someone got a hold of my PC or laptop - they would be able to do some damage, but not even close to if they were able to access my phone. Everything everywhere nowadays requires some app.