Literally never heard of any of these. However I have heard of Safari, Edge, and Firefox. And I don’t think the market share breakdown of twitter vs Mastodon is similar to Chrome vs. Firefox.
It is similar in the sense that one of the two products absolutely crushes their competition in most if not all markets and in most if not all aspects that actually matter to the end users.
Chrome has 59% global marketshare on the desktop [1][2]. That's big, but not "crushing competition so much others might as well not exist" big.
1: https://www.netmarketshare.com/browser-market-share.aspx?qpr...
2: https://www.w3counter.com/globalstats.php?year=2017&month=3
There is a reason the set contains a Twitter icon and not a Mastodon icon, a Facebook icon and not a Diaspora* icon, a CodePen icon and not a Dabblet icon, etc. Like it or not, these are the products that the people elected.