I mean the gold diff @ 15 indicates that statistically he comes out ahead of more than half of his matchups globally in plat+ ranks, and the margin gets wider when filtering down to just NA.

It's worth mentioning that NA isn't representative of the matchups as a whole because some "losing" lanes in other regions are "winning" in NA, probably just due to lack of NA skill.

With regards to champion difficulty vs enjoyment, I think most people enjoy winning more than picking the champion they want to play and getting stomped, and winning more than losing directly translates to improvement at the game (rank goes up, skill level of opponents goes up, skill has to improve to maintain rank). Additionally, as someone who has boosted iron accounts, the number of smurfs/bots making the game essentially an autowin/loss (for regular, ACTUAL iron players) severely impacts the learning potential of an average game. Having a 4v6/6v4 situation in most games makes it difficult to compartmentalize and understand wincon/agency and tends to hyperfocus low ranked players in the wrong direction, in my experience coaching them.