These two competitions seem to occur simultaneously. I feel like doing a comparison. South African (SA) teams have and are currently participating in both competitions. I believe that this post relates to an earlier one that I did (https://www.nicklieberthal.com/blog/the-six-nations-a-failed-southern-excursion)
I must admit, when I first started to watch Super Rugby - back when it was Super 12, I found it to be thoroughly enjoyable. This continued when it expanded to Super 14. However, I felt that it started to lose its' luster and prestige with the Super 15 and then 18.
The introduction of the conference system was so lame. Under this system, the SA, Australian and New Zealand teams were placed in separate groups. In addition, the SA sides would only either face the Australian OR the New Zealand teams but not both.
The introduction of the Jaguares (an Argentine side) and the Sunwolves (a Japanese side) did add some spice but it didn't feel the same. My low interest in the competition remained. I can probably pinpoint the issue to the constant tinkering of the competition. If it ain't broke, don't fix it. The introduction of the new teams can be nice but don't change the structure of the competition.
Another aspect of Super Rugby is that it doesn't lead to anything but champions. Comparisons to the Northern Hemisphere competitions (The Premiership; Top 14 and Pro Rugby), the latter was more exciting because their was qualification to an intercontinental competition within the season - first, The Heineken (H) Cup and now the Champions Cup/Challenge Cup.
These competitions pits the best Northern Hemisphere teams against eachother. The same can't be said for Super Rugby. Yes, there are strong teams but there is bound to be at least one team that will be the whipping boys. Super Rugby should've been a competition that teams should try and qualify for.
The United Rugby Championship (URC) is a whole different matter. The matches are much more exciting. Anything can happen. Every team faces each other and it alternates every season (venue wise) and the the performances of teams can differ. An example would be The Sharks. Last season they finished 8th but now they find themselves in 14th place as of this writing. They are placed in this position despite being packed with Springbok players.
Super Rugby nowadays only consists of New Zealand and Australian teams. There's also a team from Fiji and the Pacific Islands. It's known as Super Rugby Pacific. Although the COV-19 pandemic was the cause for the break-up, I'm really happy with it. The URC is always filled with surprises while Super Rugby was mostly filled with the same old thing again and again.
Watching the same thing happen again and again will cause people to turn away from it. Whether it be not attending the matches or turning off the television. People will wave off the the competition.