Is adding RNG to a game necessary to have fun?

Yes and no. Some rng can make the game exciting like drags.

Other make it more about luck than skill like deal between 1-50 damage on hit.

In a game that's more casual (like Minecraft/Terraria), yes, RNG can make the game very exciting because even if you have bad RNG, it doesn't affect you too much.

In a game like LoL, RNG is good to an extent. Like the fella up there ^ said, something like drags will make the game exciting, but things like Zoe W or even crit in some cases, can make the game less fun in a way.

Crit isn't RNG?

Remember level 2 tryn with crit runes?

He'd start

So, basically, top lane became, 'Flip a coin 3 times, if it lands tails once, you lose your lane.'

I hate RNG in league...with the exception of drakes.

yes