What grind mechanics? There's no leveling system, you can build anything anyone else can day 1. All you need is the resources or the credits to buy them. Yeah, you have go get those resources... I guess that's a grind? But that's the game. Join a group, help out, save up, and build along the way. You're able to buy a ship after a couple hours, then you can fly off to do whatever you want to do. The game seems to be focused around players having a social experience together. Being alone in a sandbox doesn't fit their goals.
As for the most relevant part of your argument: A person having to gather credits and resources to build something, then waste them to rebuild the same thing, to rinse and repeat is not fun. Not by any stretch. Yes, that is a grind. Telling that person "well the solution is to just join a group" isn't really valid because no game works like that, games have to facilitate solo play to some degree or your alienate an entire playerbase, and you also alienate any new players coming in that don't know anyone yet.
People should decide whether they're even going to have fun in the game before being shoehorned into an org just to build a ship. A lot of these "no sandbox" posts come from the sole perspective of someone in an existing organization, and you need to think of the new player experience, gameplay cycle, and how decisions affect new and solo players. They are the lifeblood of games, not established orgs who have a much higher flexibility and tolerance for change.