The only way to have a pure payment system and nothing else (zero arbitrary data) is with MimbleWimble (GRIN, BEAM).
A pure Mimblewimble chain like Grin is very inscription resistant, but Beam has added many features, some of which (smart contracts in particular) can be used to store arbitrary data [1].
[1]
https://forum.beam.mw/t/beam-inscriptions/822