"Wind the clock back 10 years or more to when everyone in the peloton was riding a steel frame bike with shallow section rims; the bike frames and wheel rims had a degree of inherent flexibility and compliance which provided comfort," says Tim Ward, Schwalbe's UK Marketing Manager. "Therefore, riding narrow 19mm wide tyres at 120 or 130 PSI was not so much of an issue,"
"Modern carbon frames and wheels, by contrast, are very much stiffer and less complaint, although they are, of course, much more efficient in terms of energy transfer from the pedals to the ground," says Tim Ward. "So, the only real way to derive a reasonable amount of comfort on a modern road race bike is through having wider tyres at lower pressure, to provide a degree of compliant suspension."
https://road.cc/content/feature/why-wider-tyres-road-bikes-are-here-stay-307245