"There is no “multiplier effect” in stocks."

No options, no futures, no margin buying, no leverage.  Somewhere the bulge bracket banks are aghast. 

In any event "You have a stock trading at $20 that pays a dividend of $1.20 shares" 

Unclear, is the dividend in cash or in shares?  US$1.20 or 1.2 shares (1.2x$20=US$24)  The delta is significant.  How exactly does either equate to " $400 in wealth" ?

"But at $10 the same twenty shares buys you 2 shares."  

The stock is trading at US$20, from whence arose $10?  How do twenty share buy 2 shares?  A reverse 10 for 1 split?

The "quarterly compounding" is a moot point, even if one assumes DRIP.  Whether HEI or NEE compounding will occur albeit at a much higher rate for the superior investment in NEE.

"HE stock traded around a small band. Until recently."

In point of fact the stock price has ranged from a low of US$13.74 to a high of US$34.30 over the last seven years. That's not a small band, that's a symphony orchestra.