That's why they are ment primarily for datawarehouse environment, definitely not for OLTP. In DW typicaly only one session is modifying any one table simultaneously (during ELT process), so locking in DW is not realy an isue. All other sessions are only performing queries on DW, there is (almost) no DML in place by "normal" users during normal operation of datawarehouse.

And I can't immagine how histograms would influence locks in any way. Histograms are only "metadata" for the optimizer to decide the optimal execution plan for queries. With DML Oracle has no choice about locking - rows that are undergoing changes (with bitmap indexes not only changing rows) must be locked with 100% predictable type of lock(s), and histograms or optimizer or execution path of how those changing rows are accessed has nothing to do with locking.