Why does this work? (auto attach)

I've been using this method to find when roblox is fully opened for a while already.

while (true)
{
    Process[] procs = Process.GetProcessesByName("RobloxPlayerBeta");
    if (procs.Length > 0 && procs[0].MainWindowHandle != IntPtr.Zero) Console.WriteLine("Roblox opened");
    else Console.WriteLine("Roblox not opened");
    Thread.Sleep(1000);
}

Video: https://cdn.discordapp.com/attachments/910497199387967488/921420913092739072/2021-12-17_23-14-25_Trim.mp4

My question is, why does this work? Because if the reasons behind this are flimsy and unreliable, then I most likely won't use it anymore (although it has yet to fail me). I could just use Process Watcher but this is much more compact imo.