Turn banking didn't used to exist, now it does, thus yes it's "modern."
I raced indoors in the 1990s and we had a 160m plywood banked track. Was that unusual? 10 laps to the mile baby! I don't think banks are new.
p.s. The banks made it fun.
160m is short, and odds are the incline angle wasn't optimal.
They are better now, and more importantly, this year a bunch of A-listers are attacking indoor like it's the end of the world. They don't normally do that.
Yared Nuguse is still slower than Kejelcha over 1500. He did the last 109m faster, but Yomif still has him beat for 1500.
These records are low-hanging fruit. The real question is, why are all these A-listers suddenly going after it
It's not about "bouncy" tracks, it's about the turns.
You'd be surprised how much force it takes to turn left for half a mile. Modern turn banking eliminates nearly all of that, so it's like running in a straight line. Gravity does the work and you get more effort into going forward.
You're not gonna see these new sub 3:50 phenoms all repeating their miracles outdoors, count on it. Jakob maybe, the others no.
The fact that Jakob and Yared have so much company in all this really means either of them could go 3:42 if they were really prepared and motivated for it. But that would just be too obvious
Why would you say, "Jakob maybe" - he's already run faster outdoors.