What I think it makes this issue more complicated is the absense of total consensus about what constitutes jhana. And I think this lack of agreement is the cause of the labelling of different definitions of jhana as sutta style, visuddhimagga style, light jhana, hard jhana, EBT jhana, and so on.
Considering the above, I seems hard to just know a priori if one’s efforts are well placed just by judging if we attain jhana or not.
What are your thoughts on this?
EDIT: You’re right about kasinas and nimitta being part of the suttas. On the former, I found some analysis suggesting that kasinas are not an EBT concept; on the latter, I remember finding the concept on some discourses, but none of them showing nimitta as a synonym for lights or something alike appearing as meditation gets deeper. I may be wrong, though, so please, correct me if that’s the case.