Why general-purpose frigates suit a multipolar world

Does the Royal Navy's general-purpose frigate plan resemble the interwar cruiser-and-sloop model?

Yes. A larger number of general-purpose ships alongside fewer high-end combatants fits the recurring need to combine regional presence, diplomacy, and credible force.

In this interpretation, the Cold War was an unusually bipolar and comparatively peaceful period, particularly for the principal powers and Europe. Conflicts elsewhere still occurred, but the rival blocs imposed a more legible structure on them; the Falklands War is an example of that structure beginning to break down. A multipolar world contains several global and regional powers whose local influence can outweigh that of a nominally stronger outsider. Numerous general-purpose frigates alongside fewer high-end combatants suit the recurring need for regional presence and diplomacy. Diplomacy here includes both soft power and the credible ability and willingness to use force. A warning loses weight when its recipient knows that no action will follow it.