What exactly is the harm? I would assume they are checking to ensure all of their hardware and software is working as intended. You're free to view something else or enjoy an entirely different activity in the interim.
If someone says the show is starting at 7:00 and I arrive at 7:00 I expect their show to start within a few minutes. If they're still checking to make sure things are working a half an hour later, they fucked up.
They have every obligation to their subscribers. Streamers are professional beggars, suggesting that they have no obligation to their viewers/subs is kind of ridiculous.
They literally don't. You are not buying the person, that is ridiculous. If you feel inclined (you're not to), you can send money because you enjoyed the stream or whatever. Throwing money at them did not create an obligation on their part. That's entitlement.
What exactly do you think the business model of streamers are? We're not talking about Joe playing baldurs gate with his 15 subscribers. We're talking about Rihanna showing up 4 hours late, drunk as fuck.