When it comes to hackers, they can get your account deleted anyway, just just the matter if they can find our weaknesses in either imgflip itself or your account. And when it comes to forgetting passwords being unable to delete your own posts and accounts, there can be legal issues in the way. imgflip is an international site meaning they have to deal with many laws all around the globe, and the EU bans the practice proposed here, this under the credo of "the right to be forgotten". Of course, there should always be a way for imgflip to verify the deleter of your account is really who they claim to be, in this case you, but completely disabling account deletion when passwords are simply forgotten can lead to legal issues.
Of course, one should in general be careful with smart phones or with computers on which you are active on open forums. In my time as moderator on many many websites I wish I had a dollar for every time I heard "my brother/sister/friend/whatever" deleted my account, or "posted the shit my account got banned for", etc. etc. etc. And I guess this proposal came forth from a similar "stunt". You can also moan about a wallet being stolen from your locker when you didn't lock it. Makes the theft just a wrong as before, but you should also have been keen to lock your locker when you put your wallet in it in the first place. Cell phones and computers should just be taken with the same care.