Yup Mrwanderlust Why not When we upload image to steemit we then get code on the Markdown editor like this
![in This bracket we need to put our keyword ](this will remain same )
This is an Random image i copied link from google
![This is my keyword](https://upload.wikimedia.org/wikipedia/commons/c/c7/GoogleLogoSept12015.png)

when you post in this way it make difference Look at this image

and read it why alt tag is better for seo.
https://www.bigcommerce.com/ecommerce-answers/what-is-an-alt-tag-and-how-does-it-impact-seo/
Resteem my Post ... if you like it .