A decade or two ago we thought that Tharsis on Mars may be an area where tectonics started but did not continue. Similarly Venus' Maxwell Montes are suggestive of the pre-tectonic volcanism. So on Venus it never even got to start but the planet did have nearly the right conditions. These facts are significant. The wisdom from those days was Mars was too cool and with a thick crust. The faults developed but the plate couldn't move significantly and eventually the crust "frozen". The hotspot eventually created the Tharsis volcanoes, Alba Patera and Olympus Mons, much later but because the crust was stuck they grew massive. Venus had a different problem it's mantle had a slightly different portion of silicates in it, this prevented strong convection currents from forming, so we had the hotspot(s) but plates never formed. That created large volcanoes but then the planet heated so much the typical type of volcanic feature changed. The crust has been recycled so often by wholesale melting we are left with just one large province of giant volcanoes.
Neither were mentioned in the article so though they fit in with the theory without a problem I wonder if they have been discounted.
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