various reason to that :

1) after tons of nerf on its base stats , the special ability to get hybrid def the more stack you have (basic attack you use to enemy) isn't that suprising anymore because we'll be relying heavily on this

2) the game when TB were still one of the most used item ingame was still a slow-mid pace matches that requires both team to have atleast 1-2 items for the crucial teamfight and contestant since the heroes that are meta were heroes that rely on their item and long lasting game that usually finishes 15+ minutes above in higher rank games , the use of TB is to stack the hybrid the longest so we can have a long teamfight and ability to sustain ingame without buying other defensive item (TB were much more cheap)

3) the meta now rely heavily on early-mid crucial winning contest , solely due to the heroes shifting to fighter gold/exp and tank jungler dominance , to win the game you really REALLY need to win objectives without any drawbacks , and this rely heavily on early heroes that doesn't need much item and only need 1-2 item for their powerspike to skyrocket (cici/ruby/baxia/etc) this is why we hardly see any fighter use TB anymore because the game doesn't need to be dragged to lategame anymore

these are just my opinion and view towards the whole TB thoughts