> It's pretty common for companies to get minority stakes in competitors to get an in.

Do you have an example of this? It will be conflict of interest and may bring anti-trust issues. No competitor will allow access to confidential information and board proceedings to be observed by competitor.

I have only seen this happening when two companies settle some legal claims (ex: QTM-Data Domain) or form partnership (not competitors, ex: MSFT-FB) when one party is private/startup and other public. Typically public company will divest the stake when startup have IPO.