How do platforms link multiple accounts?
By correlating everything two sessions have in common: IP address and subnet, device fingerprint, cookies and storage, payment instruments, and behavioural timing. IP is usually the first edge they build because it is the cheapest to compute and the hardest for a casual operator to vary.
The consequence is cascading enforcement. One account gets flagged, the graph is walked, and every account sharing that origin inherits the review. Isolating IPs does not make the other edges disappear, but it removes the one that links everything by default.