Comment by akoboldfrying

It's a legitimate question. The answer seems to be that the anchovies have a variety of glutamate salts with enjoyably different flavours.

If the only glutamate in the anchovies was MSG, or if all the glutamates in them had the same flavour and nutrition properties as MSG -- both of which were open possibilities to me before the discussion GP's question prompted -- then no, there wouldn't be much point using anchovies instead of MSG.