[vouaobrasil]

As a professional photographer, I'll say that a lot of these are just overhashed and oversimplified arguments that most photographers don't consider or even think about, with the possible exception that high ISO causes noise.

[kqr]

Sure, high ISO causes noise, but what's the alternative? Both longer shutter times and larger apertures cause blurriness, which is worse! People are way too scared of noise.

Having had to push 400 ISO film to 3200 during development, I'm super impressed by how little noise modern sensors produce. Sure, colour noise looks awful but it's also really easy to remove because humans are not really sensitive to high-frequency components of chroma anyway.

[ghaff]

Yep. The fact that I can casually "push" to 1600 or 3200 ISO at a poorly lit conference or other setting is fantastic. When I was in college, shooting at 1600 in a poorly-lit lecture hall or sports arena was about as far as I could reasonably go even playing games with development chemistry. (Could go somewhat higher but the results were generally pretty poor.)

High ISO even for relatively small sensors is an often overlooked benefit from digital photography. I got a lot of pleasure out of my many hours in a darkroom but I wouldn't go back.

[ano-ther]

Agree. Mostly, the “rules” help a beginner to understand the levers they can pull to get the intended effect. Then they can experiment and develop the artistic taste & technical experience so they can choose what to apply.

But they shouldn’t be seen as dogma. (Well, unless you do it on purpose: https://en.m.wikipedia.org/wiki/Dogme_95 )