Huh?

"The lasers typically operate in one of two bands, C or O. The former is centered at 1,550nm wavelength, while the latter is at 1,310 nm. The O band aligns with an optimal low-loss frequency through the fiber channel. The C-band range doesn’t have quite the same low loss, but it’s acceptable"

This is reversed from reality. The C-band (1550 nm) is where optical fibers have minimum losses, which is why this is the only band used for very long-haul links. The O-band (1310 nm) is where optical fibers have minimum dispersion and slightly higher losses.

Minimum dispersion means that data can be transmitted at high speed and at minimal cost (dispersion mixes adjacent symbols, so it limits the bit rate for a given cable length, unless it is compensated). For the 1550 nm band, the higher dispersion requires additional devices for dispersion compensation, but for long-haul links their cost does not matter in comparison with the savings provided by lower fiber losses.

The 1310-band can be preferable for short links because there is no need for dispersion compensation, but nowadays its main role is to provide a second frequency-separated band for bidirectional communication (upload/download) in residential Internet access through optical fibers.