Why frigate and destroyer labels blur

Have the distinctions between cruisers, destroyers and frigates blurred as navies buy more frigates?

Yes, partly: roles still matter, but navies also use the frigate label for anti-submarine focus or to frame a lighter armament.

Traditional warship categories have blurred without disappearing. Some navies reserve frigate for anti-submarine-focused combatants, while the term can also make a modest weapons fit appear more acceptable. Classification therefore communicates mission and institutional choice as much as tonnage.