A player joining a game can be placed on a planet that was part of another empire and which got completely trashed by invasions, broken trade routes or other actions. New players should not start on a trashed planet. When a player enters the game, their starting capital should have its efficiency, population, social order, TL and structures reset.
New players can get a capital with tons of ships, defenses, and advanced structures if the planet was previously owned by another player and went independent recently. They can also get a capital that is above TL 7 (and unable to build most ships without a chronimium trade route) that is in the process of reverting.
IMO it's a big problem if a new player EVER starts out with starships or ramjets on their capital The beginner's impulse is to create a fleet containing all ships because the concept that different classes have different speeds has not yet had a chance to get internalized. If the new player has starships, they will use them in the fleet and conclude that all ships are super slow, losing interest before they conquer their first planet.