TBP is a placeholder to direct the polymerase recruitment by associating with TAFs. It seems like evolution decided - for unknown reason - to incorporate TBP for cooperative binding and promoter recognition in SL1 without using its TATA affinity. Great question but there is no proper answer to your question 😅
In a way yes - if you argue that both Core and UPE are necessary. But some articles argue that UPE is not always necessary - so that means it is not necessarily always a bipartite promoter.
