Are the owners of platforms responsible for intellectual property violations if user-created content distribution is decentralized?

Consider an AI chatbot platform. If this platform doesn't allow users to create characters (that are stored on their centralized service) that infringe IP, but allows users to import character definition files that do so from external sites (that are created by community members, and may contain copyright-protected characters), without permanently storing (or storing for private use), is the owner responsible for IP infringement?