I feel that you may underestimate the amount of insider trading that goes on in private equity. Remember also, the line between insider knowledge being legal or not is somewhat gray.
I doubt there is an on record scheme with company memos and other communication discussing inside info. It's probably much closer to work friendships and casual partnerships that pass much of this information along.
As long as you can build a reasonable model to line up with the information you get, it's pretty difficult without a smoking gun to get caught.
This comment fundamentally misunderstands what insider trading is. There is no such thing as "insider trading" in private equity - insider trading by necessity is gaining an unfair advantage via non-public information. Private equity and venture capital investors both get access to substantial non-public information and are allowed to buy and sell equity in the private markets with as much or as little non-public info as they want, because that is not disadvantaging other public investors lacking that information.
While I would agree that the comment you're responding to is probably using the term incorrectly, there is definitely such a thing as insider trading in private equity.
Knowing that a public company is about to be taken private by a friend's PE firm is material non-public information (MNPI).
Knowing that a PE-backed company is about to be bought by a public strategic acquiror is MNPI.
Knowing that sales of a private company's products to a public company are changing rapidly is MNPI (think of knowing the order pipeline for an electronics manufacturer who sells to Apple).
Trading on any of this MNPI would absolutely count as insider trading, and is watched closely by PE/VC firms, who are all regulated by the SEC and FINRA (in the US, at least)
This MOI story seems to come up every few years, but McKinsey has kept everything so private that typically all the articles can say is "MIO seems suspicious, and may be conflicted"
I doubt there is an on record scheme with company memos and other communication discussing inside info. It's probably much closer to work friendships and casual partnerships that pass much of this information along.
As long as you can build a reasonable model to line up with the information you get, it's pretty difficult without a smoking gun to get caught.