A move that me, a 1200 ELO, take a minute to create, a GM takes 5 seconds.
GM is like... 2000 points above you 
what you describe is more like a 200 point gap.
In some positions, if thought all day (for 12 hours) I still might not find a move a GM could find in less than a minute.
a 1600 could lose and win and draw the same amount of games as a 1800 and still be lower
You're imagining something like a puzzle where you can just guess moves.
That's not how it works.
When you choose a move, you have to know the correct continuation / justification, otherwise it doesn't count.
Well, an 1800 is usually a lot better in positional aspects like good bishop/bad bishop, outposts, open files, etc. A 1600 may know these concepts but not necessarily put them to good use in game.
There is no good answer to this. Even among equally rated players there are differences. The obsession with rating is very prevalent in online chess because it is constantly displayed in front of your face. People should just take serious look at their own games to find out what they actually have to work on, if possible a stronger player should give them feedback on their analysis.
In OTB chess especially if you mainly play OTB team competitions you don't get to know your rating until the next season. During the season you only play your games and you don't actually know what rating you are. This is why rating was never on my mind. I rather focused on more important areas.
In online chess, there are many players who exclusively play online which means they grow up having a number going up and down in front of their face after every single game. As a consequence there is not a single day going by without one person asking any rating related questions.
Focus on improvement not rating. Labeling yourself a 1400 also limits yourself because you clearly state with your own words that you are this specific rating which isn't an accurate representation of your skills anyway.
I agree, focusing on rating is not the best way to improve. Analyzing my own games for mistakes is probably the best thing for me right now.
But our evaluation of the quality of our Chess game skills is subjective... whereas the rating gives us the objective one of that.
This is why so many people are fixated on their daily rating.
A move that me, a 1200 ELO, take a minute to create, a GM takes 5 seconds.
GM is like... 2000 points above you what you describe is more like a 200 point gap.
In some positions, if thought all day (for 12 hours) I still might not find a move a GM could find in less than a minute.
))
As for me... I find out this move never.
winning more games doesn't mean your rating will increase. it depends on the rating of the opponent