Having worked IT at an organization that works with these people, I have to disagree, unless you are very liberal with your definition of "functional".
First of all, the institutionalized ones. Just using the term "institutionalized" isn't enough to drive home just what these retards truly mean. These are people who sit in darkened rooms, motionless, shitting themselves, oblivious to the worker feeding them and wiping drool from their mouths as they stare at the fucking weather channel, all day, every day, forever.
Then you get to the violent ones, the literal animals. Picture a 20-something retard wrangler woman. You can tell she was bright and energetic when she took this job a short while ago, but today, she's scowling and looks like death would be sweet relief. The tard she has to wrangle communicates mostly in shrieks and screams. She eats a plate of mashed potatoes, and most of it gets on her face and shirt. In response to this, she screams and repeatedly bangs her palm on the table as hard as she can. Finally the wrangler just yells at the tard to put her plate in the sink. The retard drops it in the sink from a height of three feet. Miraculously it doesn't break, but it makes a loud noise. The tard screams in anger, and bangs her palm on the counter over and over. It's only now that you notice that her palm is BEAT red.
This is the REAL reality of what retards turn into. When you see the little retard at the fundraiser saying "buuuuh I wanna be a doctah", and her delusional/acting social worker beaming "AWWWW SHE HAS GOALS, DONATE PLEASE", this is what they turn into. And wrangling them is paid for, in part, by hard earned taxpayer dollars.
Now, there are slightly higher functioning ones, suited at most to tearing your ticket at the theater. But what do you call higher functioning? The adults I've seen still need wranglers. They still can't hold conversations, they still need their wrangler working supervision at their job. They will still randomly just moan out "daaaad", in a soulless voice, even though the father has been dead for three years. You may call them "high functioning", but all modern science would struggle to deem them self aware.
The worst part? Not only are those jobs ones that students could be taking to scrape up tuition, but the homes these tards are given are always, ALWAYS in great, safe, low cost neighborhoods. Shopping is near, employment is near, even a school is near, nice little yard, absolutely perfect for a young couple to start a family and live in for a decade, easy. But that house is now off the market, essentially for an entire generation, to make room for a retard who has never truly been alive.
They are little more than a complete drain on society, whether institutionalized or "higher functioning", and ALL of them should be euthanized at birth.