This is indeed a very common pattern, but not an universal one. In Ars Magica it is for instance possible to flesh out the covenant quite in detail before even starting to create any magus. I ran a D&D 5ed oneshot, where players were not allowed to make characters before they had detailed the group context and purpose, and got positive feedback on that approach.With a TTRPG group, it's exactly the opposite. You start out with no investment in the group at all, being invested solely in the one thing you know, your own character. You slowly grow attachments to the individuals who happen to adventure beside you, with the (as mentioned) "group self" notion only developing well after as a neat, desirable byproduct of becoming attached to the people who constitute that group.
Also the assumption that you know your new character better than the party breaks down if you make a new character to join a group you have played in before. This could be a common state in long campaigns with character retirement and occasional deaths. In other words, your argument here is explicitely not applying to exactly the kind of game you seem to be critizising?
Those I had in mind as restrictive is mostly lesser known indie experiments from the forge times. Maybe the most fameous one I have played that had this kind of feel to me would be prime time adventures. All you mention there are in my eyes very traditional games with basically as strong DM control as there is.I'm not really sure what restrictions PbtA games put on "reading the table" that are so onerous. Nor any other system I've played (which would include, but may not be limited to, 3e/4e/5e/PF1, a couple of retroclones, 13A, Shadowrun 5, Werewolf 20th, and an interesting obscure one called Tavern Tales where I played as an orphan in a group of children.)