I work in a Corporate where we have lots of "strategy" teams and PPTs flying around. What I learned is that PPT are more than a presentation format in this culture, they are a signaling tool: • something that is "just" an email, or "just" something somebody said in a meeting doesn't carry much weight in Corporates • .. but if you put it in a PPT with some graphics, it signals you've thought about it, and probably had…
I think it's as simple as, if you put it in a PPT, you can rest assured that it will be readable and usable by the recipient, which includes passing them along to other people, presenting it, using the slides in other presentations, and so forth. If you choose some "weird" format, then the burden is on you when someone can't use it for some reason.
PDF is what I see used when the sender is aware that not all the recipients are using Windows