Couldn't agree more! (especially for product people)
Can you give more specific details about how it helps you/the team? (no sarcasm here, I'm genuinely interested to understand this form the marketers' perspective)
If you are working remotely, you want to be able to see the latest development version and run it locally, not just the latest alpha push. In the real gritty details, I just had to update Maven on my local machine and fix a Github conflict, and had to ask for help figuring out where the missing components were and how to fix the error messages. If someone has to take an hour helping me get this done, it is unnecessary overhead. I still almost broke things in vim though, but know what I have to learn.
More generally, a technical product understanding just helps in communication. If the tech lead makes the decision to refactor the code, which leads to delays affecting the business, it's good to know why.
That's great! I'm interested mainly in these kind of benefits. Besides communication, how does it help your relationship with customers/team/partners?
The marketer needs to have enough of an idea of how the product works to be able to talk about it intelligently. "Enough of an idea," means one needs to know what the relevant parts are, and how they interact.
Imagine you are a contractor putting in a kitchen for someone, and they sometimes refer to the sink of the island and the sink on the rear counter as if they were the same thing. I wouldn't know which one they're talking about and it would drive me mad. Marketers make mistakes of this magnitude all the time.