Is Gaming Spoiler/Backseat Gaming Bad For Your Stream?

I already posted this in other Facebook pages and other forum/blog sites. As a follower/subscriber I've been watching streamers on Twitch for years as well as on YouTube Gaming, Microsoft Mixer, and Facebook Gameroom as I notice the majority streamers have their chat rules about "NO SPOILERS/BACKSEAT GAMING.....NO TIPS & GUIDES OR HINTS UNLESS I ASK FOR HELP". The burning question is: Is spoiling/backseat gaming bad for your stream? I will spoil only if there's a good reason , period. Other than that, I'll be remain quiet and enjoy your gameplay. ​I also noticed there are some streamers who are VERY exaggerated about these rules such as streamer will ban/kickout the viewer once the spoil message is visible for first time. For those sensitive streamer, I urge you not to get strategy guide, no demo or beta test game as it may contain spoiler alert just like if you wanna watch upcoming movie or TV show, don't watch previews or trailers. Or don't Googl...