First of all i have to tell you that i HATE the word "inting" because it's used for everything.
"I missed a skillshot and only traded 1 for 1" -> ah shit i am inting
"our toplane is 0/3 after 20 minutes" -> stop inting
Inting stands for intentionally feeding. And you are right! Intentionally means on purpose! And feeding... yeah you should know... giving enemy gold. (That's why i would actually count giving a nasus freefarm for 30 minutes, dancing next to him as int feeding. You give him gold without contesting.)
Again: "Int" does not stand for "EXTREMLY HIGH GRADE OF XY", it stands for "on purpose".
So let's start:
There are most likely 4 reasons, why someone is going 0/5 in 10 minutes:
1. he is actually inting
2. he is boosted -> bad for his elo
3. he has a bad game
4. he did nothing wrong and it just happened because you f'ed up yourself
Okay. And why shouldn't you flame them then and why is there even a point 4, telling you that your perfect playstlye includes some mistakes?
1. When someone is actually inting be happy about it! He gives you a free chance for learning how to play from behind!
I see so many players stop playing when their teammates going 0/5 because it's "lost anyway". These are also the people crying for 2 hours after losing
a 60 minute game in which they were behind 5k gold all the time. Would they just take the games where they play 4v5 serious, they can learn how to
ward efficiently to avoid getting catched or how to play against baron etc. And maybe they would win more of these 60 minute games.
2. You don't need to tell them they are boosted. They allready know that! I mean they lost a lot of money for beeing on an higher mmr. Just relax and let it
happen. They will fall back to their normal mmr, also losing their money. What do you lose? 18 lp and you will be back there ~5 games later. And i mean
when you play 500 rankeds in one season, what do 5 more or less count? Also, just as i said in number one, you can learn something from that game.
3. Number 3 is humanlike! Do you perform 5 games in a row consistently? And does it help you to get telled that your "mother is a %%%%ing whore who
should die on her cancer"? Is this telling you "Woah he is right! Now i am able to get my mechanics back!" I do not think so! Maybe try things like "that
was actually close, try to prevent xy or use your spell only after xy". Give them helpfull tips, THIS will make you win more games, not blaming him.
4. Okay for this one i have to give some examples.
a) You are blueside midlane against a push champion. You will go back to base just as your jungler ganks botlane. Tipically awnser of the enemy: instapush
the wave, maybe also interrupt your back one time. After that he will go to your blue, warding the jungle and also base, maybe trying to get a gank off top
with his jungler. Also the enemy jungler can coutnergank or make some crossmapplays with this vision.
solution: Only go base against a push champion when u see his manapool is on 1/3 or less and when you see him putting his trinket in his sidebushes.
As far as he don't have a pink you are fine do back now, because u can't to anything against the enemy jungler invading now. But now it's not YOUR
b) Again midlane. You see your jungler getting catched, because he is standing in a warded bush and u ping that it's warded for 30-40 seconds now. For
sure he is doing a massive mistake there but what if you don't just walk back to your lane with 250 gold and instead you would buy 3 f** pinks? So the
first one u will place in a sidebush in your mid. Just as normal. But then you see your enemy pushing and warding the "red to river"-bush to get some
vision. So what if you would just walk there, placing your second pink to clear the vision, then walk back to replace your sidepink. Sure you jsut wasted
120-140 gold, but you denied 300 gold from a kill.
c) You are playing adc. And just as every adc you got 2-3 places where to ward. Like tribush, riverbush and lanebush. So the enemy support only has to deward these spots for beeing totally fine and the jungler can come (again). Maybe you then have an Alistar supp with flash down, he headbutts away your closest enemy and will die. Again. Just walk up 10 centimeters, place a ward between drake and jungle-entrance, maybe your support checks if blastcone is up in that time and you are fine. Completely.
This can be continued over and over again...
There is no need in flaming some inting people, because in all cases you can learn from this and maybe you will have a 53% winrate instead of 51% at the end of season. Also a lot of what you are doing on your own leads to "mistakes" from your teammates. Watch your replay sometimes when you are 5/5 and your toplaner is 0/10. Because in ~20% of the cases YOU are the reason why he died that often.
Sorry for my english tho :)