It isn't designed to be small; it's designed to be a fully featured string formatting library with size as an important secondary goal.
If you want something that has to be microscopic at the cost of not supporting basic features there are definitely better options.
> I can assure you that when writing code for microcontrollers with 2 kilobytes of code space, we don't include a 14 kilobyte string formatting library...
No shit. If you only have 2kB (unlikely these days) don't use this. Fortunately the vast majority of modern microcontrollers have way more than that. E.g. esp32 starts at 1MB. Perfectly reasonable to use a 14kB formatting library there.
If you want something that has to be microscopic at the cost of not supporting basic features there are definitely better options.
> I can assure you that when writing code for microcontrollers with 2 kilobytes of code space, we don't include a 14 kilobyte string formatting library...
No shit. If you only have 2kB (unlikely these days) don't use this. Fortunately the vast majority of modern microcontrollers have way more than that. E.g. esp32 starts at 1MB. Perfectly reasonable to use a 14kB formatting library there.