Honestly the main story of the Metal Gear series isn't THAT complex. When you boil it down to the basics it's actually rather easy to follow. It becomes harder when you throw in all these ancillary characters who have their own interactions with each other that are tangentially related to the main story but don't really move it forward in any meaningful way that people get confused, not to mention the fact that this is a series of games that started in 1987 and spans 10 games, which makes it hard to remember all the details and nuances of each. In any case my point is that you shouldn't choose to not play MGS V: PP because you're worried about being lost in the story. Granted, from a timeline perspective this is episode 5 in 10, but that does mean that you don't need to know about anything starting from Metal Gear onward, which is the bulk of the story.
If you want to get up to speed I highly recommend watching this series of videos I found on YouTube. They condense the series down to what you really need to know and keep it down to the overarching story, and even reminded me of a number of things that I forgot about with the story as it had been so long since I played. It'll take you around an hour to watch. You only need to watch the first 6 videos, and I think its worth it.
https://www.youtube.com/playlist?list=PLqU3_cfWaeY2DT7imScZKA3_PZJHRfdzy
