No, primary sources are not banned on Wikipedia.

The kinds of things I offered corrections on were simple and sourced off public filings. Like the relationship of the company with another -- our company bought another, but wikipedia claimed the other company bought ours. Another obvious mistake was the picture of our building. They put a picture of the building next door. There were a number of really egregious mistakes that I tried to correct, but I got a no-comment reversion of almost all of them.

And in case you were wondering, at no time did I identify myself as an employee (and I was just a software guy anyway, not part of the marketing group), nor did they suggest that they knew I was.

Some of those reversions are automatic or semi-automatic. If you did the edits from a corporate IP address, for example, people will run that stuff down, conclude the edits are conflict-of-interest (https://en.m.wikipedia.org/wiki/Wikipedia:FAQ/Organizations), and revert them regardless of content. It appears that what Wikipedia considers the correct course of action in that circumstance is to highlight the error on the talk page and let someone else fix it.