You are missing the point. All these things may be differences (depending on ones viewpoint) but that does not make them more or less than another dance. Just elements. There are probably more elements of technique in Salsa than in AT at a high level (yes I've done AT as well), but I'm not going to argue it either way.
At a high level both would require a high level of technique. The entry level may be higher for some aspects of AT, though you don't need to learn to balance while turning fast or spinning in AT do you? You're trying to judge one dance (Salsa) by the merits of the other (AT).
The smaller the movements, the greater the necessities of fine motor control. In AT, the movements are often much smaller due to the constraints of the embrace. As a result, the accessibility of the dance is greatly limited to those who have learned this control.
The large movements in salsa that are necessary to lead does not require such fine motor control. As a result, it is much more accessible to a larger audience without as much practice.
And yes, even in AT there are turns and spins, though not often.
There is just as much requirement for lead/follow in Salsa, the balance of the elements are different that's all. ... In the same way it's absurd to say that one method of leading is more than another, different but not more.
There are many basics of leading in tango which are completely absent in salsa, which I've mentioned, which is the point of argument to say that Argentine tango is more technical than salsa. In salsa, the leader rarely transfers the follower's weight, if at all, but in AT, it is a requirement to lead. In salsa, it's possible to dance without ever making contact, alla mambo, but the tango is all about the embrace.
Leading in tango is a hell of a lot more technical than salsa.