The second one was the first iPhone with 3G networking (which had broadly been considered a required feature for smartphones when the original iPhone was introduced without it.)
I won't try to defend the 3Gs ;)
At least the N, Ns naming scheme referred to straight-forward (albeit minor) upgrades, and were released a year apart...
Not to mention X and Xs.
And the fact that they skipped 9 and will likely skip iPhone 19 as well
Microsoft skipped Window 9 too.
Samsung skipped an entire range of numbers from Galaxy S 11 to 19.
Looks like tech companies don't like 9...
Supposedly Microsoft skipped 9 because of a lot of hardcoded checks for windows 95 and 98 that checked the first digit
And the iPhone XR! All part of the twelfth-gen models. Of course the subsequent thirteenth-gen models were just called "iPhone 11" in a return to sanity.
I still don't remember what X vs XR vs XS meant. Of course I can look it up, but that's not the point.