Let me offer you a thought experiment:
I propose a champion whose ultimate ability deals zero damage but suppresses every enemy champion on cast until they or the caster is killed. This ability may sound like bullshit because it lets his team push down the nexus for free when he hits level 6, but it's not! There is plenty of available counterplay to this champion, and if you don't take one of these easily available counterpick options it's your fault that you lost.


All you need to do to beat this champion is to never let him get into a situation where he's strong!
The direction of your idea is right, but the actual statement of it is wrong. While picks/bans and items are counterplay, they should never be the primary or only form of counterplay. If you need more evidence, read through the hypothetical champion above. Since it's impossible to actually get Mercurial Scimitar or Mikhael's Crucible by the time he reaches level 6 unless you're obscenely fed, you need to pick one of those champions or take Cleanse.
If that feels like bullshit to you, it should. The thought experiment above is intended to demonstrate that just one or two counterplays is never sufficient. There are three or four stages of counterplay that every champion should have, listed below:
- Champion Select counterplay (counterpicking). If every champion has strengths and weaknesses, then there should be several champions who have strengths that target other champion's weaknesses. Alternatively, different rune and mastery choices may aid you in certain matchups.
- Itemization counterplay (counterbuilding). In order to prevent counterpicks from automatically winning games, players need to have tools to play against enemies who counter them. This usually comes in the form of itemization; for example, any champion can build armor against Riven in a bad matchup. Similarly, Riven can counterplay the enemy's counterplay by building Last Whisper.
- Standard Counterplay. Since itemization contains counters to itself, there's a chance that even choosing a specific counter build path won't help you once the opponent buys the counter item to your counter build path. However, the opponent shouldn't get an automatic win just because they counterpicked you and built the counter to your counter itemization. There's a game that works like that called Rock Paper Scissors, if that's what you're looking for. To avoid every game turning into best out of 5 rock paper scissors matches in champion select, we allow you to outplay your opponent in game by avoiding their skills or otherwise minimizing their power.
- Strategic Counterplay. Some champions are just very difficult to outplay and very difficult to outbuild, huh? Strategic counterplay zooms out of the champion on champion scenario and considers the strategy your team chooses versus the strategy the enemy chooses. So now, even though you got counterpicked by Riven and lost lane, you're okay with it because your team's Kennen/Amumu/Lissandra/Miss Fortune/Sona will crush teamfights against the opposing Riven/Master Yi/Ahri/Lucian/Thresh team. However, the opposing team has access to the same information you do and will try to avoid outright teamfights in favor of picking off your individually weak members one by one.
So with that in mind, let's look at our thought experiment again:
*Can he be counterpicked? Yes. Any champion with a Cleanse does extremely well against him, and champions with spellshields can beat him with optimal play. Champions other than his counterpicks can also select the Cleanse summoner spell to give them an opportunity to escape.
*Can he be counterbuilt? Yes. There are several items which can be built to reduce the impact of our hypothetical champion, including Banshee's Veil, Mercurial Scimitar, and Mikhael's Crucible.
*Can he be outplayed? No. Thought Experiment's ultimate hits every living enemy champion on the map regardless of position.
*Are there team-wide strategies that can be used to decrease his impact? Yes. Because Thought Experiment lacks damage and is helpless while any enemy champion remains suppressed, leaving one champion in suppression while the other four play effectively removes him from the game. This can be any champion on the team, including weaker threats like the support who may or may not be worth trading Thought Experiment for.
This champion has counterplay in three out of the four areas, right? He's got plenty of counterplay that can be used against him. Just deal with him!
**Even though he has plenty of counterplay as measured by this system, Thought Experiment is still bullshit, and would feel like bullshit to play against.**If Thought Experiment is left unbanned, the only safe champion selections are his counterpicks, many of whom are not viable in any team comp except against him (so you gimp yourself by picking them if Thought Experiment goes unpicked). Any champion who is not a counterpick MUST run Cleanse or become useless from level 6 until they can get a Mercurial Scimitar. And even then, if Mercurial Scimitar does not synergize well with the champion selected, they've wasted 3800 gold specifically to counter one ability of one champion. What do they plan to do against the rest of Thought Experiment's Team?
TL;DR:
*Strategic counterplay, counterpicks, and counterbuilds are all other aspects of counterplay in addition to the traditional definition.
*If an ability or champion lacks even one form of counterplay, or is weak in multiple areas, they become difficult to balance and overcentralizing.
*Even if a champion has a strength that can be counterpicked, counterbuilded, and is countered by a certain team comp, it should still be possible to outplay them in their situation of strength.