Wouldn't it be great if Apple had to fix vulns in older iOS versions? Than I wouldn't have to keep buying new devices. I don't buy new devices because of cool

Wouldn't it be great if Apple had to fix vulns in older iOS versions? Than I wouldn't have to keep buying new devices. I don't buy new devices because of cool features or faster speed. I buy them because my current device is vulnerable and can't handle the new iOS updates.