I'd guess that most people who think that OVF/DSLR are better than EVF/Mirrorless have not tried a current mirrorless camera.
I have been a photographer since about 1970, owned many Nikon and Hasselblad film cameras and switched to Canon digital in 2007. I now have a 5DIV and a R6 which is about 18 months old, which I sold a 1DX to buy. I rarely (almost never) pick up the 5DIV anymore. There is nothing it does better than the R6 except provide more pixels.
The R6 is the best camera I have ever owned. Battery life is not a problem in fact last Saturday I shot a local college football game. I got there at about 10:30 am and left around 2:30. I shot about 2,700 frames (about double what I wish I did) on one Canon battery.
The major camera companies have figured out mirrorless and I would never want to go back. Oh, and I use adapted lenses, which work better with my R6 than they did with my 5D cameras, so I have the entire Canon EF lens selection available to me.
Anyone looking for a 5DIV?
I've stopped shooting on a weekly basis for nearly a decade now. As utility has gone down so will my spacing out my upgrades.
My last EF body was a 2015 EOS 5Ds R which I sparingly use. If I were to upgrade it would be when the 2020 EOS R5 replacements comes out by 2024-2025.
I'd be persuaded to upgrade to an RF body today if Canon secretly designed RF L lenses to accommodate a Canon medium format camera. EF L(?) lenses that are longer than 35mm(?) can be adapted with medium format cameras.
R3 or R5 autofocus + imaging tech used in conjunction with a 100 megapixel medium format image sensor that has a crop factor of 0.79x is the dream.





