I think both things can be true.
For smaller streamers, the revenue from ads is often modest, so running midrolls is frequently more about avoiding prerolls than maximizing earnings. As streamers get larger, ad revenue becomes much more meaningful.
That's why I don't think it's as simple as "prerolls bad, midrolls good." Running 3 minutes of midrolls per hour (8-12 ads) isn't always a better experience than having a viewer watch 1-2 prerolls and then enjoy an uninterrupted session. This was my point in the interview.
There has been a lot of discussion and questions from the Twitch community recently — about viewbotting, discovery, and more. I will be going live on Thursday at 4pm PDT from my channel https://t.co/RvFw7iMABT to talk about some of these issues and answer questions.
A number of streamers have suggested that embeds are the primary viewbot vector. While this is an attack vector we monitor, embeds only account for 0.37% of total hours watched on Twitch and are not the primary source of the problem today. We have policies around embed usage and actively detect and take action against sites that violate them and will continue looking at ways to address this attack vector.