Steam recently added a knowledgebase article which officially states they are discontinuing support to two of microsoft‘s former legacy flagship operating system releases, microsoft windows xp and windows vista. Both these operating systems were released in the early 2000’s. Even in 2018, according to valves statistics, at least 0.25% of it’s user base still uses a microsoft operating system that’s older than windows 7.
Prior to windows 10, windows XP accounting for well over 10% of steams users, with gaming becoming more popular in asian countries such as china, but with windows 10 offering free upgrades, most consumers upgraded as there was no reason to stay on legacy operating systems anymore given that the upgrade was free.
So, why discontinue now in 2018?
In short, it’s stated in the source that the steam client for windows relies on google chrome, a third party browser that no longer functions on either windows xp or vista, so it’s essentially a third party software that’s finally forcing valve’s hand to terminate support. Windows XP and Vista had a good run, i’m sure many people are surprised that either were still being actively supported for steam given than both were released in the 2000’s
Official statement source:
Starting on January 1 2019, Steam will officially stop supporting the Windows XP and Windows Vista operating systems. This means that after that date the Steam Client will no longer run on those versions of Windows. In order to continue running Steam and any games or other products purchased through Steam, users will need to update to a more recent version of Windows.
The newest features in Steam rely on an embedded version of Google Chrome, which no longer functions on older versions of Windows. In addition, future versions of Steam will require Windows feature and security updates only present in Windows 7 and above.
For the remainder of 2018 Steam will continue to run and to launch games on Windows XP and Windows Vista, but other functionality in Steam will be somewhat limited. For example, new features such as the new Steam Chat will not be available. We encourage all users on these operating systems to upgrade to newer versions of Windows in order to have ongoing access to the latest features of Steam, and to ensure future access to all games and other Steam content.