Didn't the games used as examples to signify "the golden era" in this thread all use Ren'Py and Daz too? Or are you saying these tools have become easier to use? Pretty sure Ren'Py still requires you to learn rudimentary coding and I've fucked around with Daz and their UI is still a nightmare labyrinth.
I guess one point in favor of a lower threshold might be a larger proliferation of pirated Daz assets on sites like this, which was probably less available in the beginning, so you actually had to pump some money into your game if you wanted certain shit.
I don't know what "the golden era" would mean in this context, but as "back then" I meant at least 8-10 years ago. The times before Patreon and Kickstarter become so huge.
Back at the end of 2000s, even modding was a rather closed scene. Sure, there were people who made textures, but very few modders were able to make meshes, even less knew how to make animations, or change parts of the game code. There weren't widely available tools for it, and the knowledge was also missing. And that's just modding, which is far from creating a whole game.
Lately you have everything at your disposal. Animation software, character modells, tonns of assets... In 2010 if you had the story, but didn't know how to draw, or code, you needed at least an artist and a coder to help you with creating your game.
Now you really have everything. You need pictures, you learn DAZ on a basic level from YouTube tutorials, and you make them. You need some things changed in Ren'Py to match your idea, you code it. It needs such basic level coding that can be learned by anyone in a very short notice. Back then it would've taken a very long time to learn everything that's needed to create a game on your own, then you had to produce much more content for it. Now you need to learn much less, and even the production is quicker, as you get many-many things ready to use.
Don't get me wrong, I'm not saying that creating a quality game doesn't take devotion, and talent anymore. I'm just saying it used to be super hard, and now it's easier (but still not easy).