There are historical reasons for this, of course...

In Germany, "base 100" was common. 2.2, 3.2, 4.5, 6.3, 9, 13, 18, 25, 36, 50, 72, 100 ...

In France they tended to use "base 10": 2.5, 3.5, 5, 7, 10, 14, 20, 28, 40, 56, 80 ...

And the "modern" system is "base 1": 2, 2.8, 4, 5.6, 8, 11, 16, 22 (which is really closer to 23), 32, 45, 64 ...

The US (Unified System or something like that, not USA) was 1, 2, 4, 8, 16, 32 and so on - where US16 =f/16.

And of course the "reverse systems", which are proportional to either the diameter or the area. Stolze is one, another was called "French System".

Some lenses, especially casket sets and convertibles, have markings corresponding to the diameter of the aperture. Or the area. In whatever units seemed reasonable at the time.

Worst of all are what I call "AU", or "Arbitrary Units" - where the aperture settings are marked with 1, 2, 3, 4, 5, 6. Or 1, 2, 3, 4, 8, 10...