"inting"
is the act of intentionally doing something.
"feeding
is the act of supplying resources to another to provide growth and nourishment.
"intentionally feeding"
is a gaming term that means to supply resources to someone on purpose with knowledge that it will allow them to grow in strength
"intentionally feeding your opponent"
is a gaming term that is exclusive to online versus games where a player helps an opponent grow to superior levels of strength at the expense of their team WITH the knowledge that they are benefiting their opponent.
The reason why you're being accused of intentionally feeding is because you're ending the game with what is thought by the majority of the league player base as "too many deaths"
how many deaths is too many deaths in league of legends?
Riot would have to answer that by averaging the amount of deaths in non LCS matches.
as per the communities outlook on the matter - because LCS players and streamers tend to be in diamond or better it is automatically assumed that if the game lasts 30 minutes and you have 2 deaths or more then you're inting.
the community also has this idea that if you are the person that grants your opponents first blood then you're inting.
the only people allowed to carry are mid and jungle and only if they have 15 more kills than the high amount of kills on the opponents team.
intentionally feeding is pretty obvious and is determined by repetitive behavior and gameplay analysis over a series of games assuming those games get reported and reviewed.
you're more likely to be given a valid intentional feeding ban by requesting a baron duel from an opponent and losing than you are by just being unskilled.
a player that is unskilled is more obvious than players realize, but because players are focused on their own gameplay they're incapable of seeing the whole picture.
beyond everything i've said it's also just a trend at this point to blame the first person to die or anyone that you disagree with as inting just to ruffle their feathers. "you're inting" is the new "you're gay" and "your mom". It's meant to shut down an argument by attacking the person's character and puts doubt into the mind of the rest of the team. In reality it's childish, but because of the desire to fit in a lot of times duos and such will hive mind together and repeat it back and forth to one another.