Why do so many leftists love the petty bourgeoisie?

I've talked to many leftists (even self proclaimed communists) recently and one thing that unites them all is that they seem to have an affection towards the petty bourgeoisie.

I've heard someone say "small business owners put a lot of their own work into the business" to imply that small business owners are proletarian.

People get genuinely uncomfortable when I express any criticism towards small business owners or joke about small business owners forming part of the bourgeoisie.

Anyone else had similar experiences? Does anyone have explanations for this?