I would probably have done it at the start of Chapter 2 rather than the end, but Chapter 2 (on NG) is pretty short anyway. The main idea is that you have faced two (and a half) different boss types by that point and should have a good feel for how to use different legs, have a good set of weapons, etc. Which, since there is no concept of Soul Memory or even progression based matchmaking, is kind of needed to prevent people's first experience with AC6 multiplayer being the starting core getting demolished by double Zimmers.

And it isn't half the game.

What I do disagree with is holding off access to the store until late Chapter 1. But I also get that people will likely be overwhelmed by the store rather than excited, so it is probably a good approach. Let the player know how to swap out parts and what not before letting them run free. Still don't like it though.