That's a 2500km journey across 4 countries, taking about 43h by train including an overnight layover in Madrid.

And most of the journey is beelining it straight toward the destination, from Porto to Madrid, Barcelona, Narbonne, Marseille, Nice, Genova, Rome (plus minor stops along the way).

Flying is more reasonable at that distance (and likely cheaper), but I don't see how the train network is at fault here.