Which is why there are house rules and rulings. Interpretation of the rules can make a huge difference, and certain builds are going to be more effective than others. Building an effective character IMHO is not the issue.
If that is a player's sole objective, yes that makes a boring character. But as a DM, I can and should balance that out by giving the group different challenges and by giving different people different options to shine. In addition, not everyone wants to be the guy who does the most damage, some people enjoy being the support person.
There is no one way to play, and not everyone is going to enjoy every style. Back in LFR days, there was one group of gamers that always played at the same table and built all of their characters to be synergized to work together and exploit every loophole. I wouldn't have wanted to play that way but I don't think it was wrong.
But let me put this another way. Let's say I build a character that does significantly better than party average amount of damage overall. I'm not breaking (or bending) any rules. The build makes sense from a character perspective. I've even made some choices to have a more rounded character that's not totally focused on combat, they can and do contribute the the game outside of combat. I don't bully/whine/pout/argue/dominate any more than the average player.
Other than having someone who does more damage than you expect, what have I done that is wrong?