Extremely high click-through-rate isn't good generally. I can make something very vague and get high CTR but the conversion will be awful and a waste of money. For an awareness or cost per impression campaign it would be good though.

Compared to the average display ad the bright yellow grabs attention and "The night of the yellow ad" makes you curious

I am annoyed that I missed out on the opportunity to do so. Running ad-blockers has its downsides.

Incidentally, we have archive evidence of print adverts and they tell as much about how we used to live as what old newspapers do. With digital adverts there is no trace or evidence that the adverts ever existed.

Different times, different attitudes. The rash of crypto-currency adverts from last year promising untold wealth would look utterly crazy at any other time than then. Someone needs to save the adverts - including yellow squares - for posterity.