My problem with instagram, twitter, facebook and other similar sites is: you get your result, you get the likes, followers, positive comments and the thrills from it. Fast result that gives ok looking pixels. But this pleasure is short lasting. And on the end it cost me more and more time and keeps me away from the thing I should do: make some prints. So I don't have any accounts on those sites any more. For me it is always the same: I get back what I put into. Fast result - fast fading.
Of course this is only me - I am not saying everybody should do as I do

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The chief difficulty lies in crystallizing what is actually important information. It takes too much work to weed through all the garbage to get to the nuggets that matter.
Back to the pictures. Personally, when I look at a photograph I prefer to spend some time with it. It's best when it's an actual print that I can be close to, maybe even hold in my hand. A very good friend of mine took a workshop with Minor White back in the day, and one of the important exercises was to close their eyes and rest, while an easel with a work of art was placed in front of them. Then they opened their eyes, and they were to sit in front of the art work and study it for (I think) half an hour. It's amazing what you find in a single work of art in that amount of time.
Instagram, conversely, is based on mass consumption of photographs. You are of course free to flip through the pictures at your own leisure, but I very much doubt anybody spends more than 5 seconds looking at a photograph.
The contrast is startling. When I look at other people's work I prefer to spend some time with each piece, which is why I fit so poorly with the way most internet applications intends for me to look at photography.
Beforehand sorry for any typos or format incorrectness. Writing on the phone and should get tapatalk...
I tried instagram and still have the account BUT never clicked with me.
Honestly it becomes much more of a social and contact game than a talent measure. Because of what you say. A shot is seen just a few seconds and someone clicks a button.
I shown my friend, who has quite a following in there, my mobile photo work. And he was quite impressed.
However it has gotten very little attention because building up contacts is a lengthly process. And afterall it is too much cost for the small benefit.
I like and do what Thomas says. Sometimes I keep looking at a photograph for long time for all that is. Especially if I print. Then I can devote time contemplating the photo.
I do participate viewing and commenting in flickr. Sometimes I am one of the few who write relevant comments. Because a like or a "Nice shot!" Is like nothing at all.
I do not post online because of this. It all ends being a views, likes and comments game which detracts my point of photograph. Documenting and enjoying what I do.
The point of attention span. I have a classmate who views instagram to lighten some of the boring classes. She is constantly scrolling, stops for a couole of seconds, hits the heart button and resumes scrolling...
I am 20. I do know what social media can be useful but tend to keep a distance because it can become a "improductivity black hole".
I am both traditional (music, photography) but following on the leading edge in other matters (tech). Afterall this is how you know the tools.
Then people "shoo" you when you are not in a certain network. Wait and when you realise you will feel enslaved.
I feel funny and amused in my marketing course when my professor pushes us to have a constant web presence. But then he complains about all the mails...