Can we stop putting Chrome in everything? Why does it take billions of instructions and hundreds of thousands to billions of bytes of RAM to display some text and pictures?

Fair question, but there is a decent answer. It's because Steam is an app that is shipped to 3 platforms and at least 2 architectures; the web platform is a platform- and architecture-agnostic target; and there is an extremely large set of tools and large developer pool to pull from. It may not be the set of you trade-offs you would have chosen, but it's also a reasonable choice for the problem they are tackling with the set of real-world constraints they are presented with.