Most commercial platforms bill on either the count of distinct metric time series or total ingested data volume, both of which scale directly with cardinality. Adding a single customer_id tag to a metric instrumented across 20 services multiplies billable series by the total number of unique customers, often producing a cost increase that outpaces any infrastructure savings. Enforcing tagging policies at the collector layer and routing high-cardinality event data to log or object storage backends rather than a TSDB are the most direct controls available.