What is the primary reason Internet Protocol Version $4($IPv$4)$ is being slowly retired in favor of Version $6?$

It is not large enough to address all the internet devices humanity is utilizing today.

The mathematics required for converting the addresses from decimals to binary are too arduous and require too much computing power for mobile devices.

It is too slow and causes internet slowdowns that effect streaming services.

Decimal numbers are difficult to memorize and work with for network administrators.