Its simple really.
I am thinking of a board using the NRF52840 plus that already has an SPI LoRa module on it.
For possible future applications I might want to connect another SPI bus (SD card or TFT display say) a second I2C or second UART.
The NRF52840 plus does have the dedicated pins for SPI1, UART1, I2S, but then to use those ports all the dedicated pins would need to be available on an external connector.
If you were using say an ESP32S3, you could have a connector of say 2 power pins and 6 GPIOs and allocate those GPIOs either to a second SPI or MMC for SD card a second I2C or second UART, no problem.
So does the NRF52840 provide the same flexibility ?