Yeah, whenever I hear people talk of the properties of bike frame materials it reminds me of audiophiles: plenty of strong opinions backed by a remarkable absence of data.
A typical bike frame follows a truss structure: stiff and unyielding by design. Vertical compliance is going to be found elsewhere: tires, exposed seatpost, chamois/saddle, fork, handlebar, tape.
Yet, how many roadies do you find talking about suspension seatposts? It's all because in that subculture emulating present and past pro racers is seen as cool, and anything else isn't.
If you are curious, a few people like CYCLINGABOUT [0] and Overbiked Randonneuring [1] have done some measurements and the data suggests that suspension seatposts provide even more reduction in vibrations than wide tires.
[0] https://www.youtube.com/watch?v=u1e3g8uqrJU
[1] https://www.youtube.com/watch?v=rAkDaHlZQow