Re: Concrete Tornado
Tubes do (did) have an advantage for high power applications. It's easy and barely more expensive to make a giant tube. The materials are all fairly inexpensive (especially the vacuum), easy to fabricate, and the scaling works out nicely for cooling.
Tubes are tremendously disadvantaged for high frequency use. Their physical size results in high capacitance and inductance. There are clever work-arounds for some of the design challenges, but the horrible early transistors quickly displaced the best tubes for high frequency designs.