In 1971 Pakistan was severely lacking in anti-access and area-denial capabilities, especially in the face of a revolutionary new weapon - anti-ship missiles. Things have changed since then. The Hangor-class submarine program is being pursued along with many FACs precisely to guard littoral waters and to prevent close-up attacks to the shoreline and upon coastal assets. Frigates aren't necessary for this role, but for protecting SLOCs and guarding merchant ships. But Pakistan only has like 8 or 9 merchant ships, so what are the frigates protecting in war, exactly? Their main use (for now) would be to guard the submarines from aerial threats, but if the Navy believes the Arabian Sea is large enough to let 11 submarines freely move around, then we'll need to live with that decision. It isn't invalid, but just very debatable.