Yes, the provider has been removed. I am not sure which version exactly it was removed from but I don't believe it was a part of any of the 5.x distributions. I can tell you from past experience, this provider made to much 'noise' with the database and was far from being efficient. 

We removed the provided quite some time ago because it had known performance problems - there is no intent in forcing people to purhcase PE. It turned out that a relatively trivial amount of traffic could cause a bottleneck at the sql server so it was not fit for purpose. As some people continued to extract it from earlier versions and use it, we then officially deprecated it - meaning it's no longer tested, supported or developed. I'm guessing something in 5.x broke it, but no-one noticed as we don't test it anymore. In fact if you take a look at the readme.txt file in the documentation folder you'll see the following (it was actually not supported before this date, but this note was missing during packaging)

Deprecated functions
--------------------
The following items have been deprecated and are no longer supported and will not be further developed.

- The BroadcastPollingCachingProvider (June 23, 2009) was deprecated due to known performance issues. The recommended replacements are the FileBasedCachingProvider or WebRequestCachingProvider (PE only)
- The XMLLoggingProvider (June 23, 2009)  was deprecated due to known performance problems. The recommended replacement is the DBLoggingProvider (which has been the default since 3.3)

Note: SQL 2000/MSDE 2000 support was dropped wit the release of 5.2 (November 2009)