They have a very expensive, hard to replace, and high maintenance bearing at the base of the tower that carries the full force of the sail leveraged by a long moment arm. This bearing (along with lack of height = low wind) has been the reason that Flettner sails and wind turbines haven't been economical in the past.
According to your source, 1.3% of utility production comes from solar. It provides an estimate for smaller residential rooftop installations which brings total current generation closer to 2%.
[1]https://www.slashgear.com/qualcomms-cmo-anand-chandrasekher-... [2]https://www.bizjournals.com/sanjose/news/2018/09/05/intel-ce...