Why is priority_queue implemented using heaps when without using heaps too we can implement it with just vectors.

Suppose we use vector as a queue and keep the elements in decreasing order. We can use this as priority queue.

For insertion: We can use binary search. Complexity O(logN)

For deletion: Here also we can use binary search. Complexity O(logN)

For top element: O(1)

In addition, we can have access kth maximum element in just O(1) time which is not the case with heaps.

Then, why do we use heaps for implementing priority queues?