Again you're wrong because you were late to the party. Justin.tv turned into Twitch.tv during the time of Starcraft2's WoL beta. I know because I was an active watcher of these streams (people moving from Justin to Twitch) when an "unheard of" day was getting 500 concurrent viewers. According to Wikipedia it officially launched in 2011. Which honestly doesn't feel correct because I was watching WoL beta streams on Twitch and WoL released in 2010. So I was probably watching on a "beta" release of twitch. The earliest I can find any mention of a subscription button dates back to mid-2012. I can't seem to find an official release from Twitch saying it was added. This is all coming from Destiny. At the time he was probably the biggest e-celebrity who was the most transparent about his income and earnings because he was getting a "ridiculous" 1k viewers daily. He was very vocal about how his bottom line was being impacted by ad block. He was very vocal about how the fill rates on Twitch were progressively becoming worse and he also was transparent about what Azubu was promising him for fill rates. Then (again, I can't recall the exact date) he sub button came out and he explained it was a 50/50 cut. Popular streamers at the time (eg; IdrA, LzGamer, Destiny) all acknowledged while the cut seemed high they understood that twitch needed money for hardware and band and the cut seemed fair to them.
But go one with your recent knowledge and your jacking off of 13 year olds saying 'fuck' into the microphone at unheard of rates. I guess since you like to and commiserate with 13 year olds you do consider something being added 3 years ago "very long" ago