Not following the leaf-and-spine figure. 40x10G is 400G, but 4x40G is 160G, so how is this completely oversubscription free?
Edit: followed the link, it is 2.5:1 oversubscribed
Edit: followed the link, it is 2.5:1 oversubscribed
major router and switch manufacturers aren't even making new line cards with multiple 40GbE ports on them anymore, they're tech from 6-7 years ago. You can buy either something with dense 10GbE SFP+ ports, or something with QSFP/QSFP28 or similar 100GbE ports.
If you want something for a test/development lab, or are on a very tight budget, sure.
Today you'd rather use Arista 7060, 7050cx orJuniper 5200 as ToR. You'd not build 1:1, but plan for it in terms of ports and cable space, then add capacity as needed.
Almost nobody in an Enterprise environment actually needs 1:1, unlike hosters or hyperscalers renting nodes to others. Even then you'd probably being able to get away with a certain amount of oversubscription.