As you say, it being an innovation is technically arguable...
Allow me another observation then: until relatively recently (80s or 90s, I forget?), HVDC plants were entirely vacuum tube technology -- they still call 'em "valve houses", even though they're stacks of thyristors now.
If they were truly current technology, they'd have piles of MOSFETs or IGBTs or SiC in there, but that wouldn't be a good idea. Reliability and longevity are priority. Especially since you don't want to be replacing a million transistors every five years.
I wouldn't be surprised if just one of those installations could dry up the world supply of SiC devices for several years, if they had reason to push for it. Another good reason: only the most mature technology is suitable, being available in sufficient quantity, having well-established reliability, and reasonable price.
Induction heating is a somewhat parallel business too. There are still plenty of customers out there with tube oscillators. Why change it if it's still making good parts after fifty years' service? They're generally even less concerned about efficiency than the power company -- who obviously have some interest in that, being that sheer power is their bread and butter.
Tim