I have not heard the story, I personally think it’s more of a style thing than incompetence as a draftsman.....he isn’t the type of artist as the guys you mentioned, more of a stylist, and if someone is interested in getting close to “realism” Calkins isn’t for them....he’s quirky but his lines are confident enough that I trust what he does. He also creates some real weirdness that complements the strip in many cases.
Ive seen quite a few out there over the years, but not a ton....so maybe he did destroy many of them....that would be too bad IMHO
id also just throw out that Ditko could be quite odd at times, and that made for a heck of a lot of charm and humanity to his Spider-Man.