do (one) a disservice

To do something that hinders or is detrimental to one. You'll really do your kids a disservice if you cater to their every whim. Pushing through illness just does you a disservice. Take some time off to rest and recuperate. There is absolutely a segment of video game enthusiasts who create a hostile and toxic environment online, but you do the community a disservice when you dismiss the whole thing as "toxic."

do somebody a disˈservice

do something that harms somebody and the opinion that other people have of them: The minister’s comments do teachers a great disservice.