It could be argued that not having any gameplay is a flaw in itself (I wouldn't myself). However, DDLC HAS gameplay (the poem writting minigame and choosing certain dialogue options/system files). And while there's nothing wrong with the later, the minigame can be a bit confusing because there are many words that seem to fit a certain girl, but actually don't. This creates situations were your poem will not be liked by the girl of your choice despite having done nothing wrong knowingly.

Then again, many of the games that have been listed have very clear flaws. For example, Breath the Wild has poorly designed dungeons, repetitive bosses, lacks enemy variety and has very plain sidequests. And yet, like many games mentioned in this thread that also have multiple and very obvious flaws, it's still an amazing game DESPITE these flaws.

It's impossible to make a perfect game. What each one considers "perfect" is just a matter of what clicks with us personally and how much we care or tolerate the flaws of each game. For some people, having to switch between Pokémon for hours to train a new creature in classic Pokémon games is torture and bad gameplay. For others, it's just fine. In a world were almost every other JRPG every party member gains experience, this is certainly a flaw. But some care and some don't.