This appears to me to be a chumra born in the Lakewood mentality. Move outside the east coast and everyone buys from the same handful of stores that supply the entire community…and they all sell their chometz.
Not to judge, as to each his own. I just wonder how the Rabbonim of 100, or even 50 years ago would view the “chumra” culture of today. Many Rabbonim have been outspoken about the added chumras which add stress and anxiety to an already overwhelming modern society.