I used to turn down follow requests from accounts with no profile images until I realized a lot of Blind users don't use profile images. While a lack of a profile image remains one data point when assessing an account, if the account has a proper bio and I see that the person is posting regular human posts that aren't spammy, that cancels out the lack of a profile image. I'm mutuals with at least three folks who don't have one. (They're all Blind.)