No, Prep Is Not Play
An oft-cited mantra is that prep is play. Even the Starforged rulebook says it with a "Prep is Play" section. Preparing for your game is playing the game.
It is one of those things that deeply annoys me (along with "it's your game", but don't worry, phrase, we'll get to YOU later). Last I checked, playing involves actually playing the game. Somewhere along the line I missed the transition to where playing isn't playing.
Actually, speaking of that, it's interesting what this means if we extend it to everything else. If prep is play for solo gaming, then I've GMed and played a lot of games in my time, from Savage Worlds to 13th Age to Fellowship and even Dungeons & Dragons. I have never been at a table for any of those games or rolled a single die for any of them. Strangely, it seems unlikely "well, I've thought about it, I guess" would be taken as credible play experience in those circles.
Wait, how far does this prep go as far as play is concerned? The rulebook talks about it in terms of the truths and setting-making. Is it good enough if I just have the book but haven't looked at it yet? It's on my DriveThruRPG wishlist.
Prep is play caters to the social reality effect. When you announce your goals to others, and are seen as a person with goals, your brain gives you the same reward and satisfaction as if you've actually completed that goal. There's research about this phenomenon. Prep is play lets you feel like you've played the game without actually doing anything more than thinking about how nice it'd be to play a game.
So what does it actually mean to play the game in prep is play? It's not like you can join a circle discussing how the game plays, you can prep-is-play the game without engaging with the rulebook or game in any meaningful way. Like, what have you done? Who are you?
If prep is play, then I'm already losing weight by thinking about a gym membership and what calorie app to download.
The thing is, this wouldn't be such an annoying mantra to me if it was nuanced in any way. Prep is a part of play! It can and should be fun and engaging! There are different ways to do it and different styles for how you prep just like there are for how you play in general! Except those aren't what gets said. What gets said is patting someone on the shoulder for taking 3 weeks to come up with "Philabieldia" as a name for their starting setting and saying, good job, you've played an RPG.
Like... no? Am I dumb? Is looking at the back cover of a video game box at Gamestop playing the video game? Or thinking about how I'll customize my characters looks before ever getting a subscription to an MMO? When did "the ideas guy" from something we rolled our eyes at, to a validity that needs reinforced? I feel like we should be encouraging people to, like, play the game at some point, and not be afraid to get started, instead of catering to a particular anxiety of "I'm not sure I've worldbuilt/fantasized/written fanfiction enough to start my campaign".
At some point, you gotta actually engage with the material to say you've engaged with the material.