Joran from TigerBeetle here!
Yes, this is by design. SQL is a great general purpose query language for read-heavy variable-length string workloads, but TigerBeetle optimizes for write-heavy transaction processing workloads (essentially debit/credit with fixed-size integers) and specifically with power law contention, which kills SQL row locks.
I spoke about this specific design decision in depth at Systems Distributed this year: