I get it. I do, but I have a couple of points.
1. A leader is often made to be the weak link in the chain when it comes to breaking strength. It is often used as the breaking point to save and conserve the mainline braid and also due to the difficulty and strain on your equipment from breaking braid (unless very light braid). It is important to note that this is intentional breaking, like when your lure is stuck. Otherwise, you set your drag and understand that if you have 20lb braid with a 10lb leader, you assume everything is the 10lb strength and act accordingly. A properly selected and carefully tied knot virtually eliminates the possibility of connection knot failure.
2. I have also caught fish out of gin clear water with bright yellow braid and no leader, but I have also seen (anecdotally) a leader matter greatly. It is a classic case of: Will it always matter? No. Can it matter? Yes.
Visibility aside, the number one use for many of us who religiously use FC leaders is abrasion resistance. Braid, especially lower diameter braid, has poor abrasion resistance. Sometimes in wood, but primarily in rock. Thicker braid tends to do better but that is not always the case when compared to equivalent diameter mono or fluoro. It is also important to note that not all rocks are created equal, some play nicer than others, and the mean ones, well, they make it to where a leader is essential. If, and when, you experience these rocks, I promise you will understand the need. I fish a good amount of these mean rocks on lake erie where I have broken off newly tied 30lb braid by only putting the amount of pressure to lift a 3/8oz tube jig off of the bottom numerous times. Slight lift, and suddenly your line is weightless. I literally cannot fish those type of rocks with a bottom bait with braid alone.
I do agree with your philosophy of keeping it simple, because a lot of things us fisherman do are quite unnecessary. But I do believe this is a case where your experience may not reflect or represent the big picture, though your experience and wisdom is valued and certainly appreciated.