"Mis-marketing"? It clearly says what it is and what people can expect starting in the title. Then, when you actually read the thing, it becomes more than clear.
You people are just angry that it's not the full game and that's about it.
No sir, I'm not angry that it's not the full game. Making the campaign work for PC would be a significant porting challenge that is not made simple (as some would think) by bringing over the engine for a Forge PC tool. Even the full Halo 5 online experience might be over-extending the team, as although the levels could be brought over (or largely re-created within whatever limitations Forge; I'm not particularly familiar with the tools to know its cap, if any, in relation to retail maps,) the challenges of server maintenance and managing expectations for a potentially massive influx of PC players would be a huge burden on MS and 343 that would only pay off if they also had monetization methods in place to pay for it all.
What I am saying, though, is that the marketing here is that "The Halo Forge Experience Comes to Windows 10 PC", and again, I see the ensuing press release as over-embellishing and ill-describing the Forge PC application since a vital part of the Forge experience is playing your Forge designs as well as enjoying other designers' Forge creations inside the Halo multiplayer online environment. They should have been more explicit in promoting this as an Xbox One companion application for PC rather than as a PC version of the "Forge Experience".
You can make maps on PC. You can have your Xbox Live Friends (as I read it, they intentionally capitalized "Enlist the help of Friends", but hopefully I'm reading too much into how open exchanging will be in the PC Forge?) test your maps on PC. But you cannot publish and enjoy your maps with an open community and everything else Halo 5 grants Forge creators on a PC. For that part of the Forge experience*, you will need an Xbox One and a copy of Halo 5.
*EDIT -
ArsTechnica's interview on Forge for PC satisfies some of the complaints I have about the press release regarding limitations not of the app, since it does offer something more like structured gameplay than I'm giving it credit for. And also, I should give MS and 343 credit for not over-emphasizing gameplay in Forge PC since, although I do believe their intentions could have been clearer, they don't try to over-sell you that this is meant for gamers; it's meant for creators.
(BTW, I don't have a Win10 PC and at the moment don't even have my copy of Halo 5, so none of this affects me personally. I simply commiserate..)
So 343i releases a tool for their Halo 5 community on PC and it's (as I've seen numerous times) a "slap in the face"? Smh.
It's a great app, having Forge with K&M. I do need to not let my gripes about how it was announced (and just generally my lumping myself in with the crowd that's asking, "Why is MS being so weird with Halo and PC gamers?" ... I understand protecting exclusivity but there are ways of protecting the king while still giving some rooms in the castle if that's what they're interested in, like maybe releasing a F2P Halo in nations besides just Russia, or...) but in the end, it's worth celebrating what is here versus decrying what isn't. Kudos to 343 and MS for producing Forge for PC.