To elaborate a little further. So, to compile my file I have to correct my colleagues bibtex errors. But when he then sends me an updated bibtex file, I have to make the corrections all over again. Of course I could send him back his corrected bibtex file, but that has its own set of issues, and might not be popular.
As long as all collaborators use LyX (2.1) it's not a problem. They will get the bibtex errors, and will have to correct them. But if some collaborators use LaTeX, this can cause problems. The issue with bibtex somewhat breaks the compatibility between LaTeX and LyX.
