I often hear the advice to "make games, not game engines", and it's refreshing to hear it from someone who is actually working on an engine themselves, because usually when I hear this advice it's from devs who use Unity/Godot/Unreal, and the implication I get is that if you're not using one of those engines, you're wasting your time and won't ever make a game.

But I'd say there's a middle ground between using an existing engine and making your own general-purpose engine from scratch. I've been making a 2D RTS using C++/SDL, and it's taken me longer to write it this way than if I had used an existing engine, but in only a few months I've reached the point where I have a prototype and have had multiple playtests and am iterating the prototype based on feedback from those playtests.

So, while the advice "make games, not game engines" is still definitely true, it doesn't mean that if you code "from scratch" that your game will necessarily be a long 4-year engine project (unless you want it to be!). The trick is to keep the code specific to the game you're working on and to avoid the urge to abstract everything / make everything general-purpose.