An insult only goes as far as the receiver accepts it. Don't let them get to you.
That being said, a lot of people are going to hop onto this thread to tell you that either:
1."Simple champions force you to compensate due to a lack of tools", which is not true at all. You don't play Garen any differently in how you approach situations. The combo of silence into spin is always going to be the way he's played. You could make the point that knowing when to go in is the skillcheck, but knowing when to go in as say, an Amumu is just as valid. Either way you are analyzing the situation as a champion, it's just one of them had to fire a skillshot that costs mana to go in, the other right clicked.
2."Simple champions are harder because they require you to play other parts of the game" (such as the macro or the itemization parts) which makes no sense at all. Every champion in the game requires you to play other parts of the game. Dodging skillshots, splitpushing and picking items isn't exclusive to one set of champions, everyone has to do them. The part where the champion also in addition has to aim and lead the skillshots they shoot or juggle an axe or combo a barrel, that's just another ball to juggle which is why it's considered complex.
Finally, complexity in league isn't really... a thing to boast or care about. Dota has complex mechanics and heroes that require good micro of abilities and units under control, immunity interaction knowledge and strategic oversight of the entire map. This game can mostly be boiled down in gameplay to focusing on one task at a time be it simply CSing or getting your team to group up for baron. League is a casual experience at it's core. Always remember to good luck and have fun with it.
,
really an insult? should it really be considered as one? Because from my point of view it seems like the player can't figure out how to play champs such as 
or 
. That or the simplicity of the champion makes it easier for the player to figure out which results in the enemy team racking up deaths.
