Okay...fair enough. Sorry. I'm just fed up with all the gamers who whine that the game wasn't up their unrealistic expectations, and I wrongfully assumed you were one of them.
Still...your last question is a bit naive. Game companies (and especially distributors) always have to work with unfinished and/or unexisting material when they choose to fund something (if it's already finished and on the market, neither party needs funding). So as Tom mentioned, all they really needed was a good pitch and the believe that they could actually make what they said they would make.
Let's break that last part up into two...
First...the pitch. Yes, Sean communicated things in the press that clearly wouldn't be in the game and didn't correct that. However, all of that may have actually been in the planning and was decided to be cut because things weren't stable enough or would never work on a massive scale (it's not that hard to have 2 players meet each other, but a whole different ball game if thousands of people would have to be able to meet everyone else). And the other hand...there's a good reason I hardly ever follow prerelease conferences: they're basically commercials. In most cases, I just wait until the thing is ready and then read a couple independent reviews on it. And honestly: with the track record of the game industry the last couple of years, any other strategy is just setting yourself up for disappointment. However, things look even different from sony's perspective: they probably have played first beta's and had a much closer look at both the costs and what was made. And taking the team size into account and the amount of sales, I bet microsoft would still like to be in sony's position right now.
Second...the reputation. Sure, we can google hello games and just find Joe Danger (which is a pretty fun race/parkour game, btw). But what does that actually say? With the gaming industry being what it is, layoffs happen all the time, and it's not like because the layed-off ones are lazy or incapable. Hello games is not the first small company that barely has any games out (fuck...they might as well be above average if you include all the indie studio's out there), but I'm sure sony took a good look at the CV's of the employees before deciding that, with funding, they could pull off the premise of no man's sky.
Would you fund a team that has barely any reputable development experience and realistically expect a return of profit?
As a consumer: yes. I've never heard of texel raptor but I got parkitect as soon as I could. Same goes for vertigo gaming. And those are still pretty reliable, as they post nearly weekly updates on their status. I've seen things being greenlit and crowdfunded with far less credibility.