That's not true. All four major browsers can run CLR code through Silverlight [1] and depending on the statistics you use, the installation base for the plugin is in the same ballpark as Java, somewhere between 65% and 75% [2]. StatOwl even has Silverlight slightly ahead of Java at 69.7% vs 70.0% [3].
Of course, these are desktop stats. On mobile, it's a different story.
Of course, these are desktop stats. On mobile, it's a different story.
[1] http://www.microsoft.com/getsilverlight/Get-Started/Install/...
[2] http://en.wikipedia.org/wiki/Microsoft_Silverlight#Adoption
[3] http://riastats.com/
[4] http://www.statowl.com/custom_ria_market_penetration.php