While it can be argued, some consider the 80’s to be the golden era for road bikes. The typical 7 speed 13-28 pretty much was a universal gearing that offered very good gapping for the majority of riders.

As cogs were added they basically just had a higher 1st cog and filled in the gaps. If you didn’t really need the gaps filled in who wanted to make extra shifts. And a 52/13 was an easy 30mph if you could turn it, so there was less of a real need for an 11t or 12t for a lot of people.

I just never really needed to go to an 8 or 9 speed on my road bike. I still run a 7 speed, now a “3x”.

I will say that the wide range mountain bike gearing made more gears worth it. But even with that I’m running 13-40 8 speed.

John