In BOTH cases, the adc DOESN'T want to go close yet their kits fundamentally place them in the center of the enemy team.
I feel that's more a matter of trying to use them for something there kits don't focus on and aren't optimized for over them being bad.
Also I'd probably use the term "Marksman" over ADC, as marksman seems a little more accurate at the class you're describing.
The main reason to run with a marksman is there capacity to take towers and objectives while an enemy team is actively defending them, which AA range is really nifty at allowing and one of the only major concerns.
Having a solid power-spike late game is also nice, so you're solid at the time everyone's grouping up and defending objectives in the first place.
Quinn and Urgot's kits set them up to operate with the same end-game of fighters rather than marksman.
So yeah - not really viable ADCs, but at the same time neither are Nasus or Yorick, and complaining about them not being viable ADCs is kind of missing the point.
Quinn is extremely solid at split-pushing and she's very good at punishing a lot of tanky-DPS picks in top lane, which places her more in a skirmish/split-push dynamic. She's also similar to Vayne in late-game dueling potential, so it's not like she can't function more like a Riven/Yasou kind of late-game fighter.
She just plays more like a fighter/assassin than a marksman, as she's essentially more melee than range.
As for Urgot - he's mostly a tanky DPS that isn't countered by marksman during lanning like most, but rather counters marksman (and everyone else) during the lanning phase.
Dude's actually rediculously broken in Dominion due to how strong his lanning phase is (and that lasting the entire game for the bot-lane pick). Urgot's power spike is an anti-carry spike like Yorick and Lee Sin: he's all early game with his bases actually being pretty impressive and offering pretty much everything, everything in his kit just doesn't get along with item scaling so he falls off a cliff once those become really important.
Urgot is much more a lane bully like Renekton with a strong early and questionable late than he is just being a ubiquitously bad ADC. If you go with the same general build strat (1 damage item in lane, everything else tank) Urgot actually doesn't age much worse than Renekton either, and you can use his considerable CC, defensive steroids, ally-boosting armor shred, and damage-mitigation passive to transition more into an off-tank roll come late.
Anyways - calling Urgot a marksman or ADC is completly off the mark on what he does, how he scales, how he functions, and how he plays - so if you're not going to rant about Garen being a sucky mage, Leona being a sub-par ADC, and Katarina being a lackluster tank - there's not much point in complaining about Urgot being a bad marksman/ADC, because he's simply not a marksman or carry in any sense.