Not everyone is sighted. By default they get excluded from any shared image or conversation around it. The captioning feature exists to help prevent this!
It does feel silly/cumbersome typing out a literal description that recapitulates everything that’s instantly obvious to a sighted person on 1st glance at your image, but people write & support the feature hoping you will use it! no one will think less of you! it’s Mastodon cultural best practice! ⭐