Markov blankets as boundary conditions: Sweeping dirt under the rug still cleans house

Resumen:
Bruineberg et al. underestimate the ontological weight of Markov blankets as actual boundaries of systems and lean toward an instrumentalist understanding thereof. Yet Markov blankets need not be deemed mere tools. Determining their reality depends on the fundamental problem of distinguishing between system and environment in physics, which, in turn, demands a metaphysical bedrock backed by a realist stance on science.