A bird that is 200m away is going to be small even with a 600mm lens.
Again, I can only assume you have little experience with bird photography. Yes it'll be small, but 200m is by no means excessive in this genre. Also depends a lot on the size of the bird!
A 2' long bird will be 5% of a FF sensor at 200m away (where m = meters, not miles.) You're going to need a really big bird for it to take up significant sensor real estate. Which is why it doesn't interest me.
To be honest, most everything looks crap on overcast days when there is no sunlight because colors are muted. Or maybe those that shoot ISO 3200 and above don't like color very much? Would explain a lot.
Now you've way overreached. Actually lots of things look good on overcast days - sometimes they look *better* because of the reduced contrast and more neutral colours.
I can only assume that you've grown up in a part of the world where it is overcast most of the time. I've never been anywhere that looks better with neutral colors and dull gray skies. And if there are parts of the world that are overcast most of the time, so what? Just as you can't turn a pig into a princess just by adding lipstick, so too you can't make overcast days look good.
You're being excessively narrow-minded as to what constitutes normal/reasonable/acceptable photographic conditions. I'd add that you wouldn't do much shooting at all in a lot of the world if you took this attitude...
Do you have an example location for this "in a lot of the world"?
Last time I checked the photos on the front page of flickr, there were vastly more photos ISO 100-800 than there were 1600 and above.
There could be a lot of reasons for that. According to Flickr's own blog
..., the top 6 camera models for 2015 were iPhones - which don't even have ISO settings of 3200-6400. So there's a sampling bias. To state you can deduce what most DSLR customers want or need from this is... absurd, to say the least.
I counted only images taken with DSLRs, not iPhones.
So yes, canonrumors has an obsession with high ISO that is generally not representative of the wider population.
Absolutely - but you are even less representative than us, judging by what you say. And your pronouncements on the average camera buyer are at least as biased by your own experience and judgment as everyone else here.
Or maybe in not being representative of the average CR shooter I'm more representative of the average Joe.