Open-source counters most of the issues around monoculture. Remeber that the first browser wars occurred between two closed source products.

In fact, I think that a single OSS project is far more effecient than attempts at standardization across competing products when it comes to user-beneficial innovation.

Look at the open-source UNIXes. Nearly all the value-add has come from cross-pollination of "proprietary" and not-yet-standardized enhancements, which are consumed by users and application vendors targeting those platforms.