Well since even the Basic rules say that Backgrounds can be whatever you want I'm fairly certain most charopers will just halfass a Background that gives them the proficiencies they need, in particular Perception*. Oh yes, they will hound the suboptimal Backgrounds with that "trap" nonsense that makes newbies feel terrible, as is their custom. But that's a problem with the way they approach the game**, not with the system itself.
*Just kidding, charopers will all take Perception with their free Human*** skill prof
**I kid, mostly, the issue is with a select few who have a perfectly legitimate style and preference of gaming, but who feel their system mastery gives them the right to belittle those whose gaming style drives towards options for reasons other than optimization. Most charopers I know are perfectly content to allow others to design and play their characters the way they want without admonishing them for their "poor" choices.
***You were going to say "What if they don't pick Human?" but you couldn't do it with a straight face, right?
The issue with people who feel the need to optimize their PC to the point that it is always the most powerful and has few limitations is that they can wreck havoc at tables where the DM and the rest are not playing this way. A lot of times it seems subtle at low levels but as they level they become unstoppable. So as the DM I am left with bad choices either I make an encounter that the charop can't cake walk through which is usually too powerful from the others at the table or I make an encounter that is just right for the other player and the charop just cakes walk through it usually stealing all the limelight for themselves.
I have always had at least one powergamer I need to watch in every game I have run and they tend to hassle the other players for what they see as sub optimal choices. Which is why I am not thrilled if we now have another aspect that can be powergamed on charop boards.