A good example about why scientists avoid anecdote as an unreliable guide. El Hierro is a case study, not the rule, and from one example folks see what they want to see. For one, El Hierro wouldn't have been the first renewably powered island - that title was already claimed by Samso, Denmark.
https://en.wikipedia.org/wiki/Sams%C3%B8#Renewable_energy
Of course there are problems implementing engineering projects...if we used the same critique with nuclear energy or deep water drilling, neither would exist.