They're a particular tool to solve particular probems.
With green screen lit traditionally, there might be issues on the keying surface or an inability to generate an even enough light taking field. If so, using green tubes can sometimes solve the issues since you're generating specific color photons that can "wrap" around imperfections.
OTOH, if you have limited keying area or nasty geometry - then active green light can be a nightmare, spilling onto the set and causing all sorts of stuff to key poorly.
I've used them successfully, but mostly when there's a lot of control available and I'm doing greenscreen with ample subject-to-back-wall distance.
Just an alternate tool.
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