I’m not up to speed on research on masks not helping protecting against cold/flu (just Covid) so I’ll take your word for it. If masks are useless then if your sick then stay home until you aren’t contagious. If you must go out in public, just be courteous, keep distance from others and keep your hands clean at least. Minimal effort can help others not have to deal with some misery and lost days. Unless a person has a “misery loves company” mindset.
The efforts that make sense, as explained by a number of epidemiologists before they were made to stop talking, were to screen people with fever symptoms from entering stores and to provider support for isolating high risk patients from public spaces.