I think you used the right phrase, "Ability to Buy". BUT that term is sooooo subjective.
Your 'Ability to buy' will change with your creativity, not only with your credit score or income. Buying with a conventional loan is 1 way to buy. If you dont have it, find other ways.
My first house was a pre-foreclosure. The seller said he wanted to file bankruptcy. He did and it stopped the sale. I immediately before that, contracted the house. We stopped the sale, I found a buyer, double closed and made 12k. I owed 3 months of child support, recently divorced, back home living with parents, driving an old car with over 100k miles and had been recently fired from a job. Most people would say I had NO ABILITY to buy. BUT I had creativity. I bought and sold or wholesaled houses almost every month that year.
In 20+ years I have still only purchased 1 house with a conventional mortgage. That does not mean my ability to buy is not deep. It just means I dont use conventional mortgages, I have found other ways to deepen my ability to buy.
Owner finance, sub-to, partners, JV, syndication, hard money, private money, friends and some family IRA money are all ways to deepen your 'Ability to Buy'.