Honestly, this is a dumb idea. Following isn't only used to watch streamers. It is to support streamers as well. I've often followed stream I don't watch regularly watch just because I found them entertaining when one of the streams I visited often wasn't on. Just because I don't want to watch them right now doesn't mean I won't want to watch them again later. Followers also help introduce the streamer to other viewers. I sometimes browse the followed list of some of my twitch friends to find new streams to watch. The only thing your suggestion would do is greatly reduce many people's follower numbers and possibly stunt the growth of some channels.
Honestly, this is a dumb idea. Following isn't only used to watch streamers. It is to support streamers as well. I've often followed stream I don't watch regularly watch just because I found them entertaining when one of the streams I visited often wasn't on. Just because I don't want to watch them right now doesn't mean I won't want to watch them again later. Followers also help introduce the streamer to other viewers. I sometimes browse the followed list of some of my twitch friends to find new streams to watch. The only thing your suggestion would do is greatly reduce many people's follower numbers and possibly stunt the growth of some channels.