Au contraire, mon ami. This make you do the character you want to roleplay and know you'll be rewarded if you do it right.
Inspector Clouseau could be dumb in many things, but get his brightness one time or another. An low int with proficiency in investigation (maybe expertise) can cover that. But don't came with you Inspector Clouseau build that never do nothing wrong.
Isn't because you have int 8 you need to be brainless all the time, but you'll be in a lot of situations. XP for roleplaying isn't just about the stat in you sheet, is what you propose in your background, traits, ideals, bonds and flaws.
Xp for roleplaying ins't just for Int part, this can avoid abuse of metagaming, reward players that increase the content of the story, and punish players who don't follow they character concept (probably because they only did that build for min/max).
You want to play that muticlass paladin of Bahamut with Warlock Orcus patron? Fine, but I want to see your internal conflicts about that.