One of the metrics that kept me away from the Canon mirrorless system for so long was the resolution of the new R series cameras was lower than the previous DSLR cameras. I rocked a pair of 5Diii's for a long time. I didn't see the mk4 as somehting was going to improve my work much. However, the 5Div compared to the (then new) R looked like the mk 4 was the better camera. When the R5 came a long, 45mp was a bit behind the 5Ds...although the rest of the camera was a massive improvement. The R6 was only 20mp and against the 22mp of my 5Diii...it felt like a step backwards. Which is why the R8 and R6ii were the cameras for me to upgrade to.
We don't know what resoution the new R5ii will be, some say it'll be the same or there abouts (45mp). Which is fine. But those who need to push the limits of sensor resolution...45mp might not be enough. So I understand the drive for a nuvo high MP, low fps camera. It's the last bastion of the DSLR days that's left, the 5Ds still slightly outresolves the R5.