Yes I can snapshot everything if I want but the problem with the web is that it is a general purpose tool. It should be a single portal into everything both local and remote sites and applications.
Unfortunately, the rate of change is incredibly large for Internet-facing applications. Intranet-facing applications are left behind. As browsers evolve, which they do rapidly, unpredictably and without compromise[1] a disparity grows until you need two browsers. This is not a situation an enterprise wants to or can afford to maintain, simply because it's below the watermark of concern for 99% of users. This is my point.
The difference between the CLR/JVM and a web browser is that they have a predictable shelf-life and can be maintained separately as they are separate portals into each world. To be fair (I exclude the CLR from this as it's too integrated into the OS), I can ship a JVM with a Java app and it'll run quite happily for another 15-20 years.
And yes I have tried running a 16-bit VB4 (!!) app lately - one of our clients uses one. On 32-bit Windows 8.1, it still works absolutely perfectly (Windows Vista 64-bit+ has no 16-bit subsystem).
[1] Apart from IE.