There's no difference both are opinionated and both can and will drop games, streamers more so if that is not even profitable. Also maybe It's been just me watching him complaining about a damn PTR every time or being very critical of many aspects of the game by saying just as anybody else why they even added [insert random feature here] to the game because nobody asked that.
So ye they are both humans and prone to the same mistakes

Even though you say it's not a good way to test the waters, it's something that not just SE but many other companies have been spending resources on, they are using them for promotions and invite them to press events, they listen to their feedback for sure or at the very least they are interested in their opinion.
Take this however you will but it's a fact.
Or I've imagined streamers at SB press event or KH3 press event