The reason rating ends up in a spreadsheet is that changing it in the core system is slow enough to be unusable. If a rate change takes a release, it will be done in Excel instead, and the system of record stops being the system of record.
Per product, not per platform
Each product carries its own rate table with its own structure. Adding a product does not mean extending a shared model that every other product also has to live with.
Versioned, so quotes stay explainable
A rate change does not rewrite the basis of quotes already written. What a quote was priced on remains recoverable after the fact, which is what makes an underwriting file defensible in a carrier audit.
Regression-tested
Rating changes run against captured baselines, so a change intended for one product that moves the price on an unrelated one is caught before it reaches production rather than discovered in a renewal.
Rating in more depth — how rate tables are structured, versioned and maintained — is on configurable rating.