Disagree. There is far more to Twitch than just "video goes here." There's the chat system for one, which this doesn't solve for. An important part of streaming is the social aspect of it to many, in the chatroom. It's also a way for your fans to communicate back to you. Sure they can open up your stream in a browser and chat with you in a Discord, but you're talking about requiring 2 tools being open as opposed to one. And that's not even the worst part: the subscription/follower system. The goal for any greenfield streamer is to gain a follower base. These followers and concurrent viewers are what allows you to get a "subscription" button for people to pay you. Otherwise you're asking for donations via Patreon or something similar? However, if you're getting your subscription money via Patreon, you're missing out on potential boat loads of money from Twitch Prime subscribers, where every Twitch user that also has an Amazon Prime subscription can send you one free subscription per month; a LOT of Twitch streamers make a lot of additional money this way, at no additional cost to the viewer.
Things you're giving up as a greenfield streamer by rolling their own streaming platform:
* The beginning of a follower base on your destination platform (Twitch)
* A "single pane of glass" for viewing your stream, chatting with you and other viewers, and giving you subscription/donation money. This is a deal breaker for a non-negligible number of people, and your follower base might not grow as large or as quickly as you'd like.
Things you're giving up as a greenfield streamer by rolling their own streaming platform:
* The beginning of a follower base on your destination platform (Twitch)
* A "single pane of glass" for viewing your stream, chatting with you and other viewers, and giving you subscription/donation money. This is a deal breaker for a non-negligible number of people, and your follower base might not grow as large or as quickly as you'd like.
* Twitch Prime subscription money.