I see these exclusive lines as following entirely different patterns
"Netflix" WFC Trilogy was nothing more than a transplanting of WFC retail figures into a line that only existed to promote the animated series with new decos. A few new characters got put in there, but it was a fairly low effort line.
Selects is a catchall for basically anything that Hasbro thinks up. No story, just something they can throw figures at when they have nowhere they really fit into.
Velocitron Speedia 500 is a story looking for figures. It's basically Selects with a story and some new figures. Not every figure has to be a racer, they can find a position for every random figure they stick in there (flagger, road crew).
Shattered Glass is a remake of an existing story and toy theme. All figures are loose modern remakes of the original figures or can be repurposed as such (Slicer). New additions should follow the same style as the rest of the line.
Of those last three, Flamewar makes more sense as a Selects figure or even a wave 2 Velocitron figure, two lines that are nothing but random slot fillers. We know Hasbro can make pretty abrupt changes, it's how the Selects Legacy Beasts ended up as Walmart exclusives or how Netflix Bumblebee became a Walmart exclusive after VW missed the approval deadline. This wasn't a case of being something they had to commit to. There is no need for Flamewar to be in the SG line looking line plain ol' Flamewar, she's taking a slot that could have gone to someone else that does fit. It's lazy. They should have done her up in Robot Masters Road Rocket colors, it even has flames on it and arguably looks more heroic, and kept the Flamewar name. Regular Flamewar could have ended up somewhere else later.
Emerje
