If Steven was pulling in ratings like that it'd absolutely be renewed without question and we'd be getting constant marathons and new episodes every week.
I do think that the show would have consistently pulled better numbers if it had better scheduling and marketing. I think the SU promos are so off about the nature of the show - like there's this enormous disconnect between the drama of SU and the wacky "it's just a cartoon who fucking cares" vibe of CN marketing. Your post got me thinking about The Last Airbender, a show more similar to Steven Universe than Regular Show or even Adventure Time imo. TLA didn't follow the 11 minute format and it was actually correctly marketed as a family comedy that actually leaned mostly on its dramatic storytelling. Bismuth is still the only 22 minute episode to my knowledge and that's easily in the top 10.
Well, I'm still holding out hope that the crew can wrap things up in a deserving way. Maybe this is just the bitter reality of western animation that I need to swallow.
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I hate that it's so hard to even watch an episode. Hulu doesn't have season 5. Daily motion has these site links I don't fully trust. YouTube has annoying people streaming but talking over dialog. Ugh. I just wanna watch episode 20 lol.
If you don't mind associating with 4chan degenerates, I usually download the HQ files off Mega through https://sug.rocks/dl.html.