Is Drupal a real platform for an MLM at scale?

Yes, with the right architecture. Pure custom-module Drupal MLMs (Pattern A) hit performance walls around $2M GMV. Above that scale, Pattern B (Drupal Commerce front, SaaS MLM back via REST bridge) takes over and works cleanly through $50M+ GMV with no architectural changes. Pattern C (headless Drupal plus SaaS) handles networks where the editorial team is the deciding factor in keeping Drupal at all. The mistake we see most often is sticking with Pattern A past its scaling wall, which produces six months of operational pain before the team finally accepts that custom-module commission calculation isn't viable at that scale.