The sixties bring a change of complaint that is worth naming precisely, because it changes which products help. In the fifties the problem was texture — the surface was uneven and anything reflective made it more visible. In the sixties, for most people, the problem becomes flatness.
The mechanism is a drop in oil. Sebum production falls substantially, so there is less of a lipid layer holding water in and less natural slip on the surface. Skin that is short of both water and oil does not reflect light well, and the result reads as dull, papery and tired — regardless of how even the tone is.
Which inverts part of the fifties advice. In the fifties, reflective finishes were a problem because they picked out texture. In the sixties, some light return is actively useful, because the alternative is flatness. The resolution is not a dewy finish — that still picks out texture, which has not gone away — but a formula with fat in it that sits on the surface and returns light softly: a balm stick, a serum foundation, a tinted serum.
The second change is that the under-eye and the lid become genuinely thin and mobile, so the area tolerates much less product than it did. Less concealer, almost no powder, and no blurring primer under the eye.
The third is that physical handling starts to matter for many people — joints, grip strength, close vision. That is not universal in this decade and when it applies it changes which products are usable rather than which are flattering, and the easy application section is the relevant reading.