I operate two small websites, Phofee.com and LandenLove.com (formerly LandenLove.xyz, which didn’t have as many issues.)
Both domains are indexed by Google Search without any issues.
When you try to use DuckDuckGo, however, there are no results found.
This is because DuckDuckGo sources their results largely from Bing.
This is frustrating because if you do not meet some vague indexing requirements from Bing, your website will not show up in Bing search results, which includes DuckDuckGo. I would love to fix whatever issues my websites have, but Bing refuses to tell me.
They only link to a page containing 22 vague suggestions that may or may not fix your problem. If you submit a support ticket, you will be redirected to the same “help” page.
Realistically, I don’t think search engines are very useful for discovering new websites. If you want to grow your user base, it’s through advertising and other forms of promotion. HOWEVER, I am willing to bet that many users still use search engines to navigate to domains that they want to revisit. And when your site is not indexed, it’s like it never existed.
Other thoughts
Shortly before writing this post, I noticed Phofee was missing an H1 and paragraph tag on the homepage. I added these in an attempt to satisfy the indexing gods. I don’t see the point in needing these tags if search engines only index the page title and meta description. But I did it anyway.
Additionally, LandenLove.com is a very new domain that I am in the process of transferring to from LandenLove.xyz. It may simply need more time before Bing will pick it up. But I will add that Bing was refusing to do a full site crawl of LandenLove.xyz until very recently. I had to submit each blog post that I published to the Bing web master manually.