This verbiage is common at most large multinats, from my own experience and from what's been relayed to me by peers.

I never heard it at Microsoft, nor was there training about avoiding paper trails.

I was inducted within the last three years, and I remember specific recommendations by CELA to have a non-content-based email deletion policy and to never insinuate anticompetitive behavior in an email or on teams.

The implication was "don't do anticompetitive behavior, we don't need to", but the warnings were given.

Depends who you were discussing it with. In general, if it was a manager, executive, or lawyer hired post-IPO, it'd be "Let's take this offline." Pre-IPO engineer, SRE, or UX designer of any tenure and it'd be "We shouldn't be doing this."

What they probably don’t realize is the record of saying “lets take it off line” ie requesting change in communication media is suspicious in itself and much easier for humans or algorithms to find in discovery than whatever complicated scheme they were going to discuss that wouldn’t give good target keywords.

I don't know, it seems like it's probably better to take it offline than to have a whole argument about something that shouldn't be talked about in the first place. If you keep talking, they are just going to put more dubious speculation on the record.

Shutting this down is just good management.

A lot of laws are written so that you have to prove intent (for good reason) and often let’s take this offline doesn’t satisfy that requirement. There are plenty of reasons to discuss something in another forum without any intent to break any laws.

A growing company is mutually exclusive with a company that tells their employees to "not create things that will crush or destroy competitors in the first place."