I think that the big thing for the general public is not that Linux will now be easy to use/accessible, it currently is pretty much there with many different distros, it's that there's a known face behind it. In the general public Linux is just this weird thing that isn't really attached to anything besides the super tech savvy, so they think they can't use it because they aren't super tech savvy. By making it steam's Linux, they can go "oh I know steam, they do stuff really well for people like me! This is probably easy enough that I can use!"

Another thing that will help is a centralization of support. With enough people using it questions and bugs will be more common and more accessible as well as answered. Currently for you to find help for your issue you need to look for your specific distro and try to also parse if the answers for other distros would help you with your issue.