Parasitic growth — why building inside a host ecosystem works

Six mechanisms, observed in the Anki add-on ecosystem and general to any open tool ecosystem:

1. The host pre-filters your customers. Whoever installed the power tool and survived its setup guides has proven, by behavior, to be the serious minority most willing to pay for improvements. The host's difficulty is the sieve; you enter facing only sifted people, at zero acquisition cost.
2. Demand is written down. Tool ecosystems have public workflow conventions, field standards and perennial complaint threads — the forum is an open requirements document.
3. Distribution is a shelf, not a feed. Newcomers all pass through the same canonical setup guides and the host's add-on directory. Getting onto those lists is permanent placement on every newcomer's path — shelves don't scroll away.
4. Trust flows down from the host. Installing an add-on feels like customizing one's own tool, not buying from a stranger.
5. Complements refer to each other. Ecosystem tools chain rather than compete; every tool's docs name its neighbors. Slot into the chain and the chain introduces you.
6. The host will never counterattack. Open-source volunteer projects are ideologically and economically unable to build the paid convenience layer — the commercial vacuum is structural. (A cousin of the-business-model-wedge.)

The transfer formula: inherit the sieve + build from the written demand + shelve yourself into the canonical guides + join the complement chain.

The standing warning, from the same case: parasitize then defect (enclose the free thing, block the exits, ratchet prices) converts the inherited trust into resentment on a public ledger — Migaku's Trustpilot reads as the receipt.