Like any intelligent trap, it is both useful and misleading. The advantages and disadvantages are real, but they are not as restricting as a traditional rock-paper-scissors. Basically, if you level your Rock (Strength), eventually you will get a SuperRock that is capable of beating both regular paper and scissors. However, you also need to have a secondary attack stat, both because accuracy is important and because all attacks have at least 1 turn cooldown. Nothing stops you from levelling everything, but you are going to end up with three mediocre tools in that case. This wouldn't be a problem if there was no level cap, but since you have limited amount of stat points smearing them across every possible stat is going to make you weaker in the long run.So are the enemy icons for str, dex and end, there to more or less confuse you? Because it sounds like by following the attack pattern of those icons, you're just gonna develop all 3 of them at the end of the day which isn't really that viable. Like if you for a pure strength build, would the enemies with the str icon go down just as fast?
Also, attack types matter not only in the case of offence. You are just as succeptible to this mechanic when recieving attacks from enemies.