I don't understand posts like this. There are tons of games that aren't anything like D&D, in mechanics, form, genre or presentation. I don't know how you would miss them if you are even slightly interested in finding one.
Holy crap.
That's fine, Reynard, I don't understand responses like yours.
I can find other games. I'm also lucky in the fact that I have a DM is also into finding and trying new game systems. The rest of the table that I sit at doesn't know too much else about other games outside of D&D and Pathfinder. They don't know what Tales of the Valiant is, or what Level Up would bring to the table for them, or why they should be excited about Daggerheart. Yesterday, one player said "I heard you guys say OSR. What does that mean?" This was the same player who's head spun around when he saw how deadly Mothership was compared to another sci-fi game we played, Lancer. There are players and DMs who are knowledgeable and have to be both teacher and cheerleader for the game system. Couldn't tell you why the hell I'd want to play Shadow of the Weird Wizard. Hear lots of good things about 13th Age. Haven't the slightest idea how to pitch it to my group and make them want to play it versus 5e D&D.
But honestly, I even find myself struggling sometimes. Sorry, not perfect. Not as dialed in like you. Ain't got my finger on the pulse all the time. Also any idea how many people have suggested systems that, to be really nice, are so inscrutable and inaccessible that I couldn't even be fully honest with how much they just suck? I don't read every system out there just for grins.
In short, I'm not talking about me not being able to find other systems - I'm saying TTRPG designers in general often suck at marketing their game, even when they have someone in front of them asking what their game is about. SUCK at it.
Edit: And not to put it entirely on the designers of these games, the general YT, influencer community promoting said games fall into the same patterns and ruts in promoting those games also.