So what I took from that is that you probably wouldn't reach your maximum potential in the power clean without some kind of grind to complement.
Limit Strength
To reiterate, Strength is the foundation on which Power is built.
So yes, to "Reach your maximal potential in the Power Clean" increasing your Limit Strength is a vital component.
The Real Power Sport
The Olympic Lifts and Movements (Power Clean, etc) are the true power lifts. Olympic Lifts have some, if not the highest power output measured in sports...
"Olympic pull register high Power Output. Research (Dr John Garhammer/"A Review of Power Output Studies of Olympic and Powerlifting: Methodology, Performance, Prediction and Evaluation Test")
During Entire Snatch or Clean Pull Movements:
34.3 w/kg Men
21.8 w/kg Women
Second Pulls:
52.6 w/kg Men
39.2 w/kg Women
Squat and Deadlift:
12 w/kg Men
Source: "The No Deadlift, Deadlift Program"
Dr Mike Stone
Stone is regarded as one of the Guru's of Strength Training; formally working with Olympic Lifters at the US Olympic Training Center in Colorado Springs.
In an interview, Dr Mike Stone was ask what American Olympic Lifters needed to do to become better, place higher, in competition.
Stone's replied,
"They need to get stronger."
Shot Putters
Shot Putter's power output is essentially the same as Olympic Lifters.
Think of it this way. Which Shot Putter is most likely throw the farthest? The Shot Putter who Incline Presses 300 lbs and Squat 500 lbs or the the Shot Putter who Incline Presses 200 lbs and Squats 400 lbs?
The Caveat of Limit Strength Training
There is some truth to the old adage, "Strength Training makes you slow."
One of the reason for that is the Limit Strength Training converts "Super" Fast Type IIb/x Muscle Fiber over to Fast Twitch Type IIa Muscle Fiber.
That means your strength increased and your power and speed decreases.
The opposite occurs if you focus on only Power and/or Speed Training but neglect Limit Strength Training; Power and/or Speed increase while Limit Strength decreases.
Source:
A Comparison of Strength and Power Characteristics Between Power Lifters, Olympic Lifters, and Sprinters, McBride, Journal of Strength and Conditioning Research, 1999, 13(1), 58–66 q 1999 National Strength & Conditioning Association
Conjugate Training
Olympic Lifters are the Poster Children for Conjugate Training. Their training revolves around Limit Strength Training exercises and the Power Movements: Power Cleans, Power Snatches, High Pull Cleans and Snatches, Hang Pulls, Jerks, etc.
Combining Power (Olympic Lift Movements) with Limit Strength exercises increase both strengths.
...in your opinion do you think the power clean alone would be able to build a respectable amount of strength and hypertrophy in the posterior chain?
Power Cleans
The Power Cleans is predominately a Power Movement. It will build some strength but not to the same extent that heavy Deadlifts or Good Morning will in the posterior chain.
Hypertrophy
Hypertrophy Training requires sets of 8 - 12 repetitions. IF you preform Power Clean in that repetition range you will obtain some hypertrophy.
However, using a Power Clean for Hypertrophy Training amount to using a crescent wrench to drive a nail instead of a hammer.
You are using the wrong tool for the job.
Also, high repetitions with a Power Clean ensure you will develop poor technique. Technique falls apart when fatigue set in.
I remember reading somewhere that NFL players who exceed a 2 times body weight squat show no further improvement to their playing ability.
Source
It's hard to make make much of a comment on that without reading the source. You need to provide the sources of "What you heard" and "What you read". Snapshots of information like what you have stated never provide the whole picture.
Is there a similar number for the power clean?
Higher Is Better
The Power Clean is a measurement of Power.
Thus, being able to pull a greater load means you have more power than pulling a lighter load.
And how hard would it be to reach that number without the assistance of a grind?
Limit Strength
To reiterate once more, "Strength is the foundation of Power."
As Dr Mike Stone stated, American Olympic Lifter need to increase their Limit Strength in order to maximize their Olympic Lifts and place higher.
Reaching whatever "that number is" require a well written and executed program that includes Limit Strength Training and Technique Development.
Summary
1) Strength is the foundation on which Power is built. This is one point that need to be hammered home.
2) Conjugate Training that employs Limit Strength and Power Training enhances both.
Kenny Croxdale