I took these pics of holding a DS3 back in the old place...
The sticks are supposed to be held with the tip of the fingers, not with the joints, and given that the sticks are closer to each other than in DS4, I've never had an issue with thumbs stumbling with each other. Even in the middle image, where they're held towards each other, which is probably something you'd rarely do in reality, as you're more likely to view where you're going to. It might be a more common occurrence in twin-stick shooters, but it was never an issue in Resogun for me.
In comparison, the hard concave edges on the 360 pad's sticks started to hurt my thumbs after a while. The same goes for the hard convex ABXY buttons, which never happens with DS pad's flat action buttons. I actually preferred the DS3's convex sticks over the DS4's, and I've found the latter to be better after I put convex soft tips on top of them. That way my thumbs don't slip that easily in games like Resogun.
And like someone already said, if you're playing modern 3D games (e.g. Souls-likes, 3rd person action-adventures, shooters), you're more likely to hold your thumbs on the sticks the most of the time, and use the shoulder buttons for actions. Only occasionally using the action buttons for jump, dodge, or crouch. In that sense, the symmetrical design is just more natural, and that's also what Google chose, as shown in the OP.
I understand, I still preffer the Xbox designg basicaly because I grew up with that controller. When I was a kid I only had a PSX with the regular one, so maybe that's why. My first interaction with joysticks was with the Xbox. When I went back for the dual shock, the joysticks felt like... too light? I don't know how to express it, like they have almost no weight to it.