I have read comments in various threads made by official people to the effect that: experience is the main reward to be had.

This is a bit puzzling to me as experience leads to higher levels, and being higher level doesn't seem to inherently make the player better or stronger, but does impose a rising bar upon the player.

For example: early on a player will have to defeat (raid) 2 or 3 bases of level 10 or higher to earn 10 riflemen, plus a few other things like resources and speed buff. When the player gets into their 40s, they will find that bar raised to 15, and in the 60s the bar is raised again to 20s. The reward stays the same though, meaning you must do more for the same return.

Likewise, the raid a player of at least X level is set by the player's level, and is 10 below. Raiding a player of level 10 when you are level 20 is far easier than raiding a player of level 90 when you hit 100, yet the reward is still the same. I would even argue that the reward for low level players helps them to grow, being equal or larger than most of the losses they will encounter earning it, while at higher levels it is more likely to be a net loss.

I'm aware that some small rewards are also given as you level, but simply being higher level doesn't provide a game advantage, it seems to provide a disadvantage.

On the other hand, maybe the comments are geared towards players who just want bragging rights of their level. In this case, I can see that experience is indeed the most important aspect, but for me personally: I'd have not accepted a lot of those experience rewards if there had not been a competition in August to earn experience.

To put it another way: I gained experience to gain the diamonds and other items from the event, and not the other way around. Sitting at level 30 and building a huge army isn't my style of play, but part of me envies those with the patience to pull that off.