Can I build a real MLM from scratch in Laravel?

Yes, to about $2M GMV with a strong Laravel team and a unique enough comp plan that building it is a real differentiator. The genealogy queries and commission cycles are well-trodden Eloquent territory. Above $2M, comp plan complexity outpaces what's worth building yourself; the bridge pattern (Pattern B) becomes the better answer. Below those preconditions, the build-from-scratch path consumes engineering time better spent on actual differentiation, even at low GMV.