Mirrorless isn't always a good thing. 5d can probably take 3x as many pictures on a battery since it doesn't have to power a live view feed for you to compose pictures.
Well, that's what most photographers and videographers want: a big articulated screen, maybe streaming to a phone or tablet instead of peeking into a tiny viewfinder. Power? If I were in Patagonia, I'd care, but otherwise anywhere in the developed world with power outlets, cables and chargers around, no. Most people want a light camera that can could suprpass what a smartphone can do in terms of quality and ergonomics. For most of them it's the GoPro.
I know people who shoot weddings. That's all day work from breakfast till the end of the reception. They all use DSLRs with battery grips. They are already hauling in many extra batteries and charger arrays into the venue, an entire pelican case worth. For them to switch to mirrorless would mean 3 pelican cases to haul from where the bride and groom are getting ready, to the chapel, to a photoshoot location, then to the venue. That would mean a second vehicle for them. And lets consider the number of shots too vs the absolute time. A mirrorless camera in terms of shots might be good for 400 exposures at best. Shooting something like a wedding ceremony is a one take thing. You gotta get the shot, there is no asking the priest to back up again and repeat the vows, so your camera is shooting off like a machine gun and you hope one of those moments you have everyone in the frame with their eyes open without a funny look on anyones face. 400 exposures would go by in no time at all when you can take a twelve exposure burst in a few seconds.
There is a reason why when you see any big sporting event or anything with professional photographers these days, you still see a sea of DSLRs despite mirrorless cameras like the A7 having excellent sensors on the market for 10 years now.
I fidn many mirrorless cameras don't have anywhere near as good physical handling characteristics. I am a Canon guy and I'd rather deal with my full size dslr over my tiny canon mirrorless...and it's not like the mirrorless is small once you add a 17-40. Or 24-70 on to it. They're just not as ergonomic and convenient to stabilize - I use a shoulder stabilized style when using a 70-200 and just can't pull it off with a mirrorless camera.
The mirrorless cam tends to just be a travel camera and only sees the 14mm pancake lens on it most of the time.
I own a 5D4 and an R5. I haven't really used the R5 more than a few times, but I'm already having a hard time going back to my 5D4, between features and everything. Battery is less of an issue for me because I've typically used the battery grip, on either.
For more compact travel stuff, I bought a Leica Q a few years ago, that has a fixed 28mm.
